Bug 510818 - Dark blurs are significantly brighter than they were in Plasma 6.4
Summary: Dark blurs are significantly brighter than they were in Plasma 6.4
Status: RESOLVED FIXED
Alias: None
Product: kwin
Classification: Plasma
Component: effects-window-management (other bugs)
Version First Reported In: 6.4.91
Platform: Ubuntu Linux
: HI normal
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords: regression
: 510903 511035 511040 511047 511053 511170 511412 (view as bug list)
Depends on:
Blocks:
 
Reported: 2025-10-20 09:09 UTC by John Mickelonis
Modified: 2025-11-13 16:29 UTC (History)
32 users (show)

See Also:
Latest Commit:
Version Fixed/Implemented In: 6.5.3
Sentry Crash Report:


Attachments
Blur disabled on the left, and enabled on the right. (613.68 KB, image/png)
2025-10-20 09:09 UTC, John Mickelonis
Details
Blur effect on 6.4 / 6.5 (77.80 KB, image/png)
2025-10-22 14:25 UTC, Efe Ciftci
Details
Merged screenshots of blur on and off (3.57 MB, image/png)
2025-10-22 15:48 UTC, PQCraft
Details
kwin v6.5.0 patch to add "Use contrast settings" option to blur plugin (10.83 KB, patch)
2025-10-23 13:31 UTC, John Mickelonis
Details
Blur comaprison in KDE 6.4.5 vs 6.5 (827.74 KB, image/png)
2025-10-26 12:21 UTC, agarplayerarlon
Details
Illustration to my comment 32 (382.28 KB, image/jpeg)
2025-10-29 16:36 UTC, Menak Vishap
Details
Blur broken in Plasma 6.5.1 (435.60 KB, image/png)
2025-10-29 19:43 UTC, medin
Details
Blur not fixed Plasma Wayland 6.5.2 (379.51 KB, image/png)
2025-11-09 13:24 UTC, medin
Details

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Description John Mickelonis 2025-10-20 09:09:37 UTC
Created attachment 185917 [details]
Blur disabled on the left, and enabled on the right.

SUMMARY
In Plasma 6.5 betas as well as Neon unstable (6.6), the blur effect is broken.
It appears to add brightness to the content behind it.

STEPS TO REPRODUCE
1. Enable Blur effect
2. Make menus transparent
3. View menus or shutdown/logoff background

OBSERVED RESULT
Blurred content appears way brighter than normal.

EXPECTED RESULT
No brightness should be added.

SOFTWARE/OS VERSIONS
KDE Plasma Version:
6.4.91+
KDE Frameworks Version:
6.18.0+
Qt Version: 
6.9.0+

ADDITIONAL INFORMATION
Screenshots are from a fresh install of KDE Neon Unstable.
In Application Style->Breeze, I set Transparency to full.
In Desktop Effects->Blur, I set Blur and Noise strength to Light (though other settings do not alleviate the issue).
I also tested Kubuntu Beta PPA as well as my own kde-builder Plasma install, which both looked the same.
CPU is a Ryzen 5600x.
GPU is a Radeon 6700 XT.
Comment 1 Efe Ciftci 2025-10-22 14:25:22 UTC
Created attachment 186005 [details]
Blur effect on 6.4 / 6.5

I can confirm that the blur effect appears different in Plasma 6.5. The attached image shows a comparison of Yakuake with translucency and blur enabled. In Plasma 6.5, the blur effect looks noticeably brighter and more saturated compared to Plasma 6.4.
Comment 2 PQCraft 2025-10-22 15:48:56 UTC
Created attachment 186012 [details]
Merged screenshots of blur on and off

I can also confirm. Here's 2 screenshots (merged into 1 image) of the color when blur is enabled and when it's disabled.
Comment 3 Vlad Zahorodnii 2025-10-23 07:02:26 UTC
The blur and background contrast effects got merged in 6.5
Comment 4 John Mickelonis 2025-10-23 11:48:18 UTC
Poked around the kwin code, and apparently early code changes had an option to disable the forced contrast, but they removed it:
https://invent.kde.org/plasma/kwin/-/commit/ddc7f8f123a1cf0be9724e1e10296a5138970272

It would've been nice to at least have a hidden kwinrc setting we could tweak. I hope they'll reconsider.
Comment 5 John Mickelonis 2025-10-23 13:31:03 UTC
Created attachment 186043 [details]
kwin v6.5.0 patch to add "Use contrast settings" option to blur plugin

Apply this patch to kwin to add a "Use contrast settings" option to the blur plugin.
Comment 6 PK 2025-10-23 17:19:13 UTC
I made a bug rapport about this before I see this bug rapport https://bugs.kde.org/show_bug.cgi?id=510903
I don't at all recognize kde/plasma in this change. Imho the whole thing became ugly and there is no choice.
Comment 7 The Feren OS Dev 2025-10-23 17:30:46 UTC
Can reproduce

Feren OS's Plasma Style always opted out of the contrast effect in its Plasma Style because the contrast effect caused it to be brightened to a dark grey instead of black, which looks ugly.

Especially in its upcoming Inspire 4.0 design where there is more established borders around Plasma elements, the contrast effect is not needed, makes the theme ultimately look worse than without due to the aforementioned brightening of the theme that isn't desired, and should be able to opt out of contrast again.

Inspire never needed neither brightening contrast nor darkening contrast due to the fact it's designed to be its own contrast-substitute - I apologise for not raising this in the merge request as I missed it, but I really do need this option back.
Comment 8 Rotlug 2025-10-23 19:00:48 UTC
I also want to express my dissatisfaction with the way this contrast setting looks and the inability to disable it. Please consider adding the toggle back in :).
Comment 9 Daniel Dvergsnes 2025-10-24 11:45:28 UTC
I just got the update to 6.5 on Arch Linux today and I regret updating. I use a theme that relies a lot on the blur effect and now it all looks bad because of this change, even the blurry black background I have in Konsole looks light gray at its darkest when what's behind it is pitch black.

Please fix or add an option to have blur work like it did before. There's no way to have any kind of dark blur with the way it is now.
Comment 10 pcrosa 2025-10-24 13:02:52 UTC
Please revert this change or add a toggle, this looks awful.
Comment 11 mith3113 2025-10-24 19:51:24 UTC
Please allow the background contrast effect to be disabled. I'm using the third party Better Blur effect but background contrast being forced on is still causing issues.
Comment 12 Appu Mon 2025-10-24 19:55:21 UTC
Can confirm and can reproduce. KDE, please fix this!
Comment 13 Shariar Rahman 2025-10-24 21:04:35 UTC
Confirming this

This is even more apparent in the log-off / shutdown menu that you get when using ctrl+alt+de. 
I think it is a tint shift as well as an increase in saturation and contrast. This was not needed. It was fine before. 
Changing the blur strength or blur noise amount has not effect.

It is a weird look. A slight change in contrast and saturation is fine but this is moving the slider too far. It's jarring.
Comment 14 Zamundaaa 2025-10-24 22:12:35 UTC
*** Bug 511053 has been marked as a duplicate of this bug. ***
Comment 15 Zamundaaa 2025-10-24 22:14:58 UTC
*** Bug 511035 has been marked as a duplicate of this bug. ***
Comment 16 Maximilian Böhm 2025-10-25 01:09:24 UTC
My bug 511035 got marked as duplicate of this bug but I was also complaining about the gutter gray veil in context menus with Breeze theme.
Comment 17 shira 2025-10-25 11:30:16 UTC
i opted to use a different blurring plugin (Better Blur) instead but it would be nice if they could add the option to disable the forced contrast back. very glaring flaw on an otherwise stellar release (so far)
Comment 18 medin 2025-10-25 22:17:46 UTC
For me the blur effect is totally broken in all parts of Plasma desktop and appears opaque (lighter gray).

Operating System: Manjaro Linux 
KDE Plasma Version: 6.5.0
KDE Frameworks Version: 6.19.0
Qt Version: 6.10.0
Kernel Version: 6.17.5-1-MANJARO (64-bit)
Graphics Platform: Wayland
Comment 19 medin 2025-10-25 23:04:22 UTC
Another effect which helps to show text on transparent background, I used it with Blur effect, but in 6.5 it was gone.
Comment 20 agarplayerarlon 2025-10-26 12:21:14 UTC
Yeah the blur changed in 6.5 and it looks very ugly now!
I will add an attachment on how it looks now in 6.5 compared to 6.4.5

Please KDE team fix the blur in 6.5 and make it look like it always used to look!
Comment 21 agarplayerarlon 2025-10-26 12:21:51 UTC
Created attachment 186181 [details]
Blur comaprison in KDE 6.4.5 vs 6.5
Comment 22 Bug Janitor Service 2025-10-27 07:58:44 UTC
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kwin/-/merge_requests/8311
Comment 23 Niccolò Venerandi 2025-10-27 11:36:00 UTC
*** Bug 511040 has been marked as a duplicate of this bug. ***
Comment 24 Bug Janitor Service 2025-10-27 13:07:00 UTC
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kwin/-/merge_requests/8313
Comment 25 PK 2025-10-27 13:20:38 UTC
Now I'm being dead serious and not in any way cynical or bitter. And the last thing I would want to do is to step on anybodies toes:
I read here https://invent.kde.org/plasma/kwin/-/merge_requests/8311 
- the background contrast effect and the blur effect got merged to
simplify the overall design and corresponding protocol bits, and to
improve performance,
and
- This change introduces a hidden UseContrast option and disables the
background contrast effect until we figure out what the best strategy
to handle this is
In the more than twenty years that I use plasma/kde I never felt the need to use it. And I never saw anybody else do so too. Wouldn't it be an option to not offer this ContrasEffect anymore?
Comment 26 agarplayerarlon 2025-10-27 13:24:53 UTC
(In reply to PK from comment #25)
> Now I'm being dead serious and not in any way cynical or bitter. And the
> last thing I would want to do is to step on anybodies toes:
> I read here https://invent.kde.org/plasma/kwin/-/merge_requests/8311 
> - the background contrast effect and the blur effect got merged to
> simplify the overall design and corresponding protocol bits, and to
> improve performance,
> and
> - This change introduces a hidden UseContrast option and disables the
> background contrast effect until we figure out what the best strategy
> to handle this is
> In the more than twenty years that I use plasma/kde I never felt the need to
> use it. And I never saw anybody else do so too. Wouldn't it be an option to
> not offer this ContrasEffect anymore?

yes it's the same thing I was thinking but I just didn't want to write it in the merge request, but yeah, I've never felt the need to have the contrast effect, the blur in KDE has always looked pretty and perfectly fine to me, they shouldn't need to fix something that is not broken.

I just want them to revert the changes that made the blur so ugly in 6.5 and let it be how it has always been, as I've said, no need to fix something that is not broken.
Comment 27 Zamundaaa 2025-10-27 15:21:24 UTC
*** Bug 511170 has been marked as a duplicate of this bug. ***
Comment 28 Marco Martin 2025-10-27 16:01:00 UTC
Git commit e039d6c48dc41f04de92f590bccddd8cdd5d6cc3 by Marco Martin.
Committed on 27/10/2025 at 15:33.
Pushed by mart into branch 'master'.

Only keep the saturation component from the old contrast effect

The contrast component can cause weird flashing frames while
a surface with a blur fades in on top of another one.
just keep the saturation effect, making the intensity configurable,
and by default and tone it a bit down to make the final result look
as close as possible to the old effect with the contrast enabled

M  +5    -17   src/plugins/blur/blur.cpp
M  +2    -3    src/plugins/blur/blur.h
M  +3    -0    src/plugins/blur/blur.kcfg

https://invent.kde.org/plasma/kwin/-/commit/e039d6c48dc41f04de92f590bccddd8cdd5d6cc3
Comment 29 Marco Martin 2025-10-27 19:37:28 UTC
Git commit ec003486ddcd9fd078cc76e7f650e16e65de2bc4 by Marco Martin.
Committed on 27/10/2025 at 19:37.
Pushed by mart into branch 'Plasma/6.5'.

Only keep the saturation component from the old contrast effect

The contrast component can cause weird flashing frames while
a surface with a blur fades in on top of another one.
just keep the saturation effect, making the intensity configurable,
and by default and tone it a bit down to make the final result look
as close as possible to the old effect with the contrast enabled

M  +5    -17   src/plugins/blur/blur.cpp
M  +2    -3    src/plugins/blur/blur.h
M  +3    -0    src/plugins/blur/blur.kcfg

https://invent.kde.org/plasma/kwin/-/commit/ec003486ddcd9fd078cc76e7f650e16e65de2bc4
Comment 30 Logan Turner 2025-10-28 04:05:29 UTC
I see this too. It looks terrible with the super high saturation. If there's any way to disable it, that would be much appreciated.
Comment 31 pallaswept 2025-10-28 04:43:07 UTC
I've just gone through everyone's screenshots and realised mine might be the worst of the lot. If someone's trying to fix this, and wants a good litmus test: Try black background. Hope that's helpful.
Comment 32 Menak Vishap 2025-10-29 16:31:34 UTC
It seems, that the problem is not solved completely. In Plasma 6.5.1 it looks a bit better in Wayland session, but, unfortunately, nothing changed in X11 session as compared with 6.5.0. And in Wayland session excessive saturation still appears in blur region. If it is possible, just return previous behaviour (like in 6.4.5 and earlier) at least in X11 session. Tested on Plasma 6.5.1 under openSUSE Leap 15.6.
Comment 33 Menak Vishap 2025-10-29 16:36:36 UTC
Created attachment 186302 [details]
Illustration to my comment 32

Here is illustration to my previous comment
Comment 34 Daniel Dvergsnes 2025-10-29 17:27:51 UTC
(In reply to Menak Vishap from comment #32)
> It seems, that the problem is not solved completely. In Plasma 6.5.1 it
> looks a bit better in Wayland session, but, unfortunately, nothing changed
> in X11 session as compared with 6.5.0. And in Wayland session excessive
> saturation still appears in blur region. If it is possible, just return
> previous behaviour (like in 6.4.5 and earlier) at least in X11 session.
> Tested on Plasma 6.5.1 under openSUSE Leap 15.6.

It looks a lot better for me than it did before on Wayland (I don't use X11), in terms of contrast it looks like it did before. I agree that the saturation is a bit more than before, but if you read the commit this is now configurable and the default value is set to 3. You can change it in ~/.config/kwinrc under [Effect-blur] by adding Saturation=1 to that section. I think 1 looks like it did before, but you can tweak it until you're happy.
Comment 35 medin 2025-10-29 19:43:26 UTC
Created attachment 186304 [details]
Blur broken in Plasma 6.5.1

It's still broken in Plasma 6.5.1.

Operating System: Manjaro Linux 
KDE Plasma Version: 6.5.1
KDE Frameworks Version: 6.19.0
Qt Version: 6.10.0
Kernel Version: 6.17.5-1-MANJARO (64-bit)
Graphics Platform: Wayland
Comment 36 Nate Graham 2025-10-29 21:19:41 UTC
In 6.5.1, we played with the standard settings a bit, but the underlying issue remains. We're discussing what to do about it and should have a plan soon that restores the appearance to what it was in Plasma 6.4, at least for people using the default settings.
Comment 37 Nate Graham 2025-10-29 21:25:40 UTC
*** Bug 511047 has been marked as a duplicate of this bug. ***
Comment 38 Nate Graham 2025-10-29 21:28:57 UTC
*** Bug 510903 has been marked as a duplicate of this bug. ***
Comment 39 agarplayerarlon 2025-10-29 22:14:56 UTC
(In reply to Nate Graham from comment #36)
> soon that restores the appearance to what it was in Plasma 6.4, at least for
> people using the default settings.

thank you so much!
Comment 40 Bug Janitor Service 2025-10-30 06:54:06 UTC
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kwin/-/merge_requests/8330
Comment 41 Vlad Zahorodnii 2025-10-30 18:38:05 UTC
Git commit c27a92ef574cd2a662117010a43a603107bdf384 by Vlad Zahorodnii.
Committed on 30/10/2025 at 17:22.
Pushed by vladz into branch 'master'.

Revert "Blur: Add a configuration UI for the contrast amount"

This reverts commit 1f953976e9a6f82133f7421964cfbc3f55583cc1.

M  +0    -66   src/plugins/blur/blur_config.ui

https://invent.kde.org/plasma/kwin/-/commit/c27a92ef574cd2a662117010a43a603107bdf384
Comment 42 Vlad Zahorodnii 2025-10-30 18:38:08 UTC
Git commit bab8f21a7cf3e34f3532a1f7f7b0d80638d9df15 by Vlad Zahorodnii.
Committed on 30/10/2025 at 17:22.
Pushed by vladz into branch 'master'.

plugins/blur: Make contrast opt-in

This restores 6.4 look for surfaces other than plasma surfaces.

M  +44   -6    src/plugins/blur/blur.cpp
M  +8    -3    src/plugins/blur/blur.h

https://invent.kde.org/plasma/kwin/-/commit/bab8f21a7cf3e34f3532a1f7f7b0d80638d9df15
Comment 43 Vlad Zahorodnii 2025-10-30 18:38:15 UTC
Git commit 9bc9b2ea1a0ab2e3ecb7698e3d1c28e18914873e by Vlad Zahorodnii.
Committed on 30/10/2025 at 17:22.
Pushed by vladz into branch 'master'.

Revert "Only keep the saturation component from the old contrast effect"

This reverts commit e039d6c48dc41f04de92f590bccddd8cdd5d6cc3.

M  +17   -5    src/plugins/blur/blur.cpp
M  +3    -2    src/plugins/blur/blur.h
M  +0    -3    src/plugins/blur/blur.kcfg

https://invent.kde.org/plasma/kwin/-/commit/9bc9b2ea1a0ab2e3ecb7698e3d1c28e18914873e
Comment 44 pallaswept 2025-10-31 08:13:58 UTC
(In reply to pallaswept from comment #31)
>  If someone's trying to fix this, and wants a good litmus test: Try black background. Hope that's helpful.

Just got 6.5.1 and re-enabled blur, it's fine here. I don't know if it's identical to 6.4 but I don't care about that. The colour scheme is intact, it's good to go. Thanks devs!
Comment 45 Nate Graham 2025-10-31 18:16:35 UTC
*** Bug 511412 has been marked as a duplicate of this bug. ***
Comment 46 kaminata 2025-10-31 19:42:06 UTC
It's interesting that I had no problems in 6.5.0 but I have in 6.5.1. Very strange...
Comment 47 Logan Turner 2025-11-01 03:15:34 UTC
I think instead of having the contrast be a binary on/off option, maybe it could be a slider built into the blur options which allows users to set it to what they think looks best, or off entirely.
Comment 48 PK 2025-11-01 06:25:21 UTC
(In reply to kaminata from comment #46)
> It's interesting that I had no problems in 6.5.0 but I have in 6.5.1. Very
> strange...

Could it be possible that you need to "change ~/.config/kwinrc under [Effect-blur] by adding Saturation=1 to that section"? As explained in comment 34 of this bug rapport... 
I my case this worked 100%. Only, I had to reboot/sign off/on to let the change take effect.
Comment 49 kaminata 2025-11-01 08:40:06 UTC
(In reply to PK from comment #48)
> (In reply to kaminata from comment #46)
> > It's interesting that I had no problems in 6.5.0 but I have in 6.5.1. Very
> > strange...
> 
> Could it be possible that you need to "change ~/.config/kwinrc under
> [Effect-blur] by adding Saturation=1 to that section"? As explained in
> comment 34 of this bug rapport... 
> I my case this worked 100%. Only, I had to reboot/sign off/on to let the
> change take effect.

I tested it but it has no effect at all. Here's my bug with screenshots:
https://bugs.kde.org/show_bug.cgi?id=511412
Comment 50 Bug Janitor Service 2025-11-03 09:10:02 UTC
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kwin/-/merge_requests/8350
Comment 51 Vlad Zahorodnii 2025-11-03 09:48:56 UTC
Git commit b7a07f47a01e2329b2ede4f42f691b7dbf714487 by Vlad Zahorodnii.
Committed on 03/11/2025 at 09:10.
Pushed by vladz into branch 'Plasma/6.5'.

Revert "Only keep the saturation component from the old contrast effect"

This reverts commit e039d6c48dc41f04de92f590bccddd8cdd5d6cc3.
(cherry picked from commit 9bc9b2ea1a0ab2e3ecb7698e3d1c28e18914873e)

M  +17   -5    src/plugins/blur/blur.cpp
M  +3    -2    src/plugins/blur/blur.h
M  +0    -3    src/plugins/blur/blur.kcfg

https://invent.kde.org/plasma/kwin/-/commit/b7a07f47a01e2329b2ede4f42f691b7dbf714487
Comment 52 Vlad Zahorodnii 2025-11-03 09:49:05 UTC
Git commit f703816ec5a77985a7a90e54e62463f2b5dd3dff by Vlad Zahorodnii.
Committed on 03/11/2025 at 09:10.
Pushed by vladz into branch 'Plasma/6.5'.

plugins/blur: Make contrast opt-in

This restores 6.4 look for surfaces other than plasma surfaces.
(cherry picked from commit bab8f21a7cf3e34f3532a1f7f7b0d80638d9df15)

M  +44   -6    src/plugins/blur/blur.cpp
M  +8    -3    src/plugins/blur/blur.h

https://invent.kde.org/plasma/kwin/-/commit/f703816ec5a77985a7a90e54e62463f2b5dd3dff
Comment 53 John Mickelonis 2025-11-03 21:38:12 UTC
So the "fix" has been reverted again?

We're going to have forced contrast again for 6.5.2, with no way to change it back (via hidden kwinrc config or anything).

The bug report title was even changed out from under me, and the intention completely missed.  I reported this bug BECAUSE IT AFFECTED PLASMA.  Now the fixes are forcing contrast for plasma and fixing everything else? 

This is beyond frustrating.  Guess we'll have to patch things ourselves or use Better Blur.
Comment 54 John Mickelonis 2025-11-03 21:44:12 UTC
(In reply to Daniel Dvergsnes from comment #34)
> It looks a lot better for me than it did before on Wayland (I don't use
> X11), in terms of contrast it looks like it did before. I agree that the
> saturation is a bit more than before, but if you read the commit this is now
> configurable and the default value is set to 3. You can change it in
> ~/.config/kwinrc under [Effect-blur] by adding Saturation=1 to that section.
> I think 1 looks like it did before, but you can tweak it until you're happy.

The configurable saturation has been removed, too.  In 6.5.2, this will no longer work.  Saturation is again forced along with contrast.
Comment 55 PK 2025-11-04 05:53:23 UTC
(In reply to John Mickelonis from comment #54)
> (In reply to Daniel Dvergsnes from comment #34)
> > It looks a lot better for me than it did before on Wayland (I don't use
> > X11), in terms of contrast it looks like it did before. I agree that the
> > saturation is a bit more than before, but if you read the commit this is now
> > configurable and the default value is set to 3. You can change it in
> > ~/.config/kwinrc under [Effect-blur] by adding Saturation=1 to that section.
> > I think 1 looks like it did before, but you can tweak it until you're happy.
> 
> The configurable saturation has been removed, too.  In 6.5.2, this will no
> longer work.  Saturation is again forced along with contrast.
I see you point John. And I also see that you, like me, try to read the content of this bug rapport well and that is not easy. With all those long numbers and so on
- Git commit 9bc9b2ea1a0ab2e3ecb7698e3d1c28e18914873e  
- commit bab8f21a7cf3e34f3532a1f7f7b0d80638d9df15 
- reverted 
- pushed
and so on. But I really hope you're wrong!
Comment 56 medin 2025-11-04 09:02:00 UTC
(In reply to John Mickelonis from comment #53)
> So the "fix" has been reverted again?
> 
> We're going to have forced contrast again for 6.5.2, with no way to change
> it back (via hidden kwinrc config or anything).
> 
> The bug report title was even changed out from under me, and the intention
> completely missed.  I reported this bug BECAUSE IT AFFECTED PLASMA.  Now the
> fixes are forcing contrast for plasma and fixing everything else? 
> 
> This is beyond frustrating.  Guess we'll have to patch things ourselves or
> use Better Blur.

The new change in Plasma 6.5 completely broke blur on my laptops, blur simply appears as brighter solid gray, and many people reported the same regression. It's for the best to completely revert the change before code changes many times and becomes difficult to revert.

The same mistake done with night light should not be repeated.
Comment 57 John Mickelonis 2025-11-05 01:21:26 UTC
(In reply to medin from comment #56)
> The new change in Plasma 6.5 completely broke blur on my laptops, blur
> simply appears as brighter solid gray, and many people reported the same
> regression. It's for the best to completely revert the change before code
> changes many times and becomes difficult to revert.
> 
> The same mistake done with night light should not be repeated.

I agree that if something was broken for you, it should be fixed.

All of these changes have broken something for many people.  And now we're left with a closed bug report, a number of disappointed people, a forced/wildly different default, and no way to configure any of it.

I'd prefer to not need to use Better Blur, but at this point, I'm glad it exists.
Comment 58 Menak Vishap 2025-11-06 23:16:41 UTC
Unfortunately, in Plasma 6.5.2 in X11 session we still have the same horrible ugly look as in 6.5.1 and 6.5.0. :( Please, return look of Plasma 6.4.5 in X11 session. I can not use Wayland session permanently because of problems with multiple national keyboard layouts, so I do need the normal appearance of X11 Plasma session.
Comment 59 kaminata 2025-11-08 22:28:16 UTC
It seems it's not the old behaviour for it's not working on X11. On Wayland the problem is fixed but not on X11.
Comment 60 agarplayerarlon 2025-11-09 11:06:13 UTC
Finally the blur looks normal again in 6.5.2 at least on Wayland, thanks!
Comment 61 medin 2025-11-09 13:24:50 UTC
Created attachment 186646 [details]
Blur not fixed Plasma Wayland 6.5.2

The blur is not yet fixed in Plasma Wayland 6.5.2, it looks the same brighter gray color, see attached image for more info.


And kwin_wayland throws a number of errors in journald:


11/9/25 2:12 PM	kwin_wayland	Failed to compile fragment shader: 
 "0:19(18): error: could not implicitly convert operands to arithmetic operator\n0:19(17): error: operands to arithmetic operators must be numeric\n\x00"
11/9/25 2:12 PM	kwin_wayland	line 0:"uniform sampler2D texUnit;"
11/9/25 2:12 PM	kwin_wayland	line 1:"uniform mat4 colorMatrix;"
11/9/25 2:12 PM	kwin_wayland	line 2:"uniform float offset;"
11/9/25 2:12 PM	kwin_wayland	line 3:"uniform vec2 halfpixel;"
11/9/25 2:12 PM	kwin_wayland	line 4:""
11/9/25 2:12 PM	kwin_wayland	line 5:"varying vec2 uv;"
11/9/25 2:12 PM	kwin_wayland	line 6:""
11/9/25 2:12 PM	kwin_wayland	line 7:"void main(void)"
11/9/25 2:12 PM	kwin_wayland	line 8:"{"
11/9/25 2:12 PM	kwin_wayland	line 9:"    vec4 sum = texture2D(texUnit, uv + vec2(-halfpixel.x * 2.0, 0.0) * offset);"
11/9/25 2:12 PM	kwin_wayland	line 10:"    sum += texture2D(texUnit, uv + vec2(-halfpixel.x, halfpixel.y) * offset) * 2.0;"
11/9/25 2:12 PM	kwin_wayland	line 11:"    sum += texture2D(texUnit, uv + vec2(0.0, halfpixel.y * 2.0) * offset);"
11/9/25 2:12 PM	kwin_wayland	line 12:"    sum += texture2D(texUnit, uv + vec2(halfpixel.x, halfpixel.y) * offset) * 2.0;"
11/9/25 2:12 PM	kwin_wayland	line 13:"    sum += texture2D(texUnit, uv + vec2(halfpixel.x * 2.0, 0.0) * offset);"
11/9/25 2:12 PM	kwin_wayland	line 14:"    sum += texture2D(texUnit, uv + vec2(halfpixel.x, -halfpixel.y) * offset) * 2.0;"
11/9/25 2:12 PM	kwin_wayland	line 15:"    sum += texture2D(texUnit, uv + vec2(0.0, -halfpixel.y * 2.0) * offset);"
11/9/25 2:12 PM	kwin_wayland	line 16:"    sum += texture2D(texUnit, uv + vec2(-halfpixel.x, -halfpixel.y) * offset) * 2.0;"
11/9/25 2:12 PM	kwin_wayland	line 17:""
11/9/25 2:12 PM	kwin_wayland	line 18:"    gl_FragColor = (sum / 12) * colorMatrix;"
11/9/25 2:12 PM	kwin_wayland	line 19:"}"
11/9/25 2:12 PM	kwin_wayland	line 20:""
11/9/25 2:12 PM	kwin_wayland	line 21:""
11/9/25 2:15 PM	systemd-coredump	Process 1678 (plasmashell) of user 1007 dumped core.

Stack trace of thread 1678:
#0  0x00007f79cf204f54 n/a (n/a + 0x0)
ELF object binary architecture: AMD x86-64

11/9/25 2:16 PM	kwin_wayland	Failed to compile fragment shader: 
 "0:19(18): error: could not implicitly convert operands to arithmetic operator\n0:19(17): error: operands to arithmetic operators must be numeric\n\x00"
11/9/25 2:16 PM	kwin_wayland	line 0:"uniform sampler2D texUnit;"
11/9/25 2:16 PM	kwin_wayland	line 1:"uniform mat4 colorMatrix;"
11/9/25 2:16 PM	kwin_wayland	line 2:"uniform float offset;"
11/9/25 2:16 PM	kwin_wayland	line 3:"uniform vec2 halfpixel;"
11/9/25 2:16 PM	kwin_wayland	line 4:""
11/9/25 2:16 PM	kwin_wayland	line 5:"varying vec2 uv;"
11/9/25 2:16 PM	kwin_wayland	line 6:""
11/9/25 2:16 PM	kwin_wayland	line 7:"void main(void)"
11/9/25 2:16 PM	kwin_wayland	line 8:"{"
11/9/25 2:16 PM	kwin_wayland	line 9:"    vec4 sum = texture2D(texUnit, uv + vec2(-halfpixel.x * 2.0, 0.0) * offset);"
11/9/25 2:16 PM	kwin_wayland	line 10:"    sum += texture2D(texUnit, uv + vec2(-halfpixel.x, halfpixel.y) * offset) * 2.0;"
11/9/25 2:16 PM	kwin_wayland	line 11:"    sum += texture2D(texUnit, uv + vec2(0.0, halfpixel.y * 2.0) * offset);"
11/9/25 2:16 PM	kwin_wayland	line 12:"    sum += texture2D(texUnit, uv + vec2(halfpixel.x, halfpixel.y) * offset) * 2.0;"
11/9/25 2:16 PM	kwin_wayland	line 13:"    sum += texture2D(texUnit, uv + vec2(halfpixel.x * 2.0, 0.0) * offset);"
11/9/25 2:16 PM	kwin_wayland	line 14:"    sum += texture2D(texUnit, uv + vec2(halfpixel.x, -halfpixel.y) * offset) * 2.0;"
11/9/25 2:16 PM	kwin_wayland	line 15:"    sum += texture2D(texUnit, uv + vec2(0.0, -halfpixel.y * 2.0) * offset);"
11/9/25 2:16 PM	kwin_wayland	line 16:"    sum += texture2D(texUnit, uv + vec2(-halfpixel.x, -halfpixel.y) * offset) * 2.0;"
11/9/25 2:16 PM	kwin_wayland	line 17:""
11/9/25 2:16 PM	kwin_wayland	line 18:"    gl_FragColor = (sum / 12) * colorMatrix;"
11/9/25 2:16 PM	kwin_wayland	line 19:"}"
11/9/25 2:16 PM	kwin_wayland	line 20:""
11/9/25 2:16 PM	kwin_wayland	line 21:""
Comment 62 Tech-Tac 2025-11-09 18:14:06 UTC
I can confirm, still too bright (in dark mode) as of 6.5.2
Comment 63 Victor 2025-11-10 11:19:43 UTC
Just updated to 6.5.2 and blur now is much brighter :/
Comment 64 medin 2025-11-12 10:06:22 UTC
If everything was reverted, did something changed in the configuration after upgrading and need to be manually reverted by user?
Comment 65 Victor 2025-11-12 10:33:47 UTC
Maybe it's because one of the first things I do when installing a system with Plasma is to disable contrast, and apparently now I no longer have an option for that. The ideal  would be to customize the same as Better Blur with Contrast, Saturation and Brightness.
Comment 66 medin 2025-11-12 12:22:11 UTC
With Plasma Wayland 6.5.2, blur only works in SDDM and lock screen, but appears as bright gray in other parts like launcher, panel, task tooltips, tray widgets, audiotube...

I tested with kernel 6.6.116 and got the same results.

I even installed that effect Better Blur from https://github.com/taj-ny/kwin-effects-forceblur but it failed to render blur like the default Blur effect.
Comment 67 Bug Janitor Service 2025-11-12 17:09:06 UTC
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kwin/-/merge_requests/8425
Comment 68 Vlad Zahorodnii 2025-11-12 17:09:47 UTC
plasma/kwin!8425 should fix the fragment shader not compiling.
Comment 69 Vlad Zahorodnii 2025-11-13 07:33:30 UTC
Git commit b4dd72662a9eced714219020aff4cee1c4447ae5 by Vlad Zahorodnii.
Committed on 13/11/2025 at 07:01.
Pushed by vladz into branch 'master'.

plugins/blur: Fix contrast.frag

GLSL is very nitpicky about implicit conversions, we need to use "12.0".

M  +1    -1    src/plugins/blur/shaders/contrast.frag

https://invent.kde.org/plasma/kwin/-/commit/b4dd72662a9eced714219020aff4cee1c4447ae5
Comment 70 Vlad Zahorodnii 2025-11-13 08:14:01 UTC
Git commit 89907486efc3f64c7f55988569265ed69bb262d4 by Vlad Zahorodnii.
Committed on 13/11/2025 at 07:43.
Pushed by vladz into branch 'Plasma/6.5'.

plugins/blur: Fix contrast.frag

GLSL is very nitpicky about implicit conversions, we need to use "12.0".


(cherry picked from commit b4dd72662a9eced714219020aff4cee1c4447ae5)

Co-authored-by: Vlad Zahorodnii <vlad.zahorodnii@kde.org>

M  +1    -1    src/plugins/blur/shaders/contrast.frag

https://invent.kde.org/plasma/kwin/-/commit/89907486efc3f64c7f55988569265ed69bb262d4