Bug 455812

> Every time the wallpaper changes, the panel and dock flash opaque, the window shadow
> becomes far darker for a moment, and various other graphical glitches occur
I have a feeling something is refreshing KWin when the wallpaper changes. Does the issue happen when Latte Dock isn't running? If not, then the issue is caused by Latte Dock manually refreshing KWin when the wallpaper changes.

> Additionally, certain icons (in this case, folder icons with thumbnails) don't update to reflect
> the new accent color, while others do.
This is a separate bug; see Bug 454049.

(In reply to Nate Graham from comment #1)
> > Every time the wallpaper changes, the panel and dock flash opaque, the window shadow
> > becomes far darker for a moment, and various other graphical glitches occur
> I have a feeling something is refreshing KWin when the wallpaper changes.
> Does the issue happen when Latte Dock isn't running? If not, then the issue
> is caused by Latte Dock manually refreshing KWin when the wallpaper changes.

Yep, I just tested it without Latte Dock and that refresh is still occurring on every wallpaper change. (Also, as I'm writing this, I *just* noticed that the refresh also freezes the window contents for a moment before fading into the new content. I didn't catch that initially, but it's worth mentioning as it makes the transition extremely jarring and disorienting.)

> > Additionally, certain icons (in this case, folder icons with thumbnails) don't update to reflect
> > the new accent color, while others do.
> This is a separate bug; see Bug 454049.

Ah - my bad, I thought this might be a system-wide issue, as it also happens in the Plasma desktop folder view. But I guess that's handled by the same code Dolphin uses?

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(In reply to Keith from comment #2)
> Ah - my bad, I thought this might be a system-wide issue, as it also happens
> in the Plasma desktop folder view. But I guess that's handled by the same
> code Dolphin uses?

The code is actually different.

Is this still happening in Plasma 5.25.3?

(In reply to Nate Graham from comment #4)
> (In reply to Keith from comment #2)
> > Ah - my bad, I thought this might be a system-wide issue, as it also happens
> > in the Plasma desktop folder view. But I guess that's handled by the same
> > code Dolphin uses?
> 
> The code is actually different.
> 
> Is this still happening in Plasma 5.25.3?

Yes - I just emerged the 5.25.3 update and can confirm that the bug is still present, with or without Latte Dock running. The only thing that has gone away is the header bar colour not matching the rest of the UI (which I believe was reported in a separate bug).

Ultimately we should probably turn off the Blend effect when using slideshow wallpapers, as it causes other problems too. That would fix this.

*** Bug 455501 has been marked as a duplicate of this bug. ***

I don't know if this could be related to bug 414097 which is about the icon color of some folders in Dolphin not automatically changing with accent color changes.
Other than that, I also experience visual glitches in the header (tab) bar of Brave web browser with system GTK+ theme.  Sometimes its color changes only partially, sometimes it doesn't change at all, until I click on it. Hovering on it also causes a similar partial change, again until I click on it (as seen in the screenshot attached). This doesn't happen in other apps using GTK theme like LibreOffice, Thunderbird, Palemoon web browser, etc.
Note: I would very much prefer living with these minor visual glitches to losing this very attractive dynamic accent color feature though. ;-)

Created attachment 152523 [details]
Visual glitches in the header (tab) bar of Brave web browser with system GTK+ theme

That's a separate issue; see Bug 456874.

I see similar stutters using accent colors and slideshows on Plasma 5.26, on KDE neon. It is noticeable as Video playback monetarily pauses/skips during wallpaper changes.

I don't have Latte Dock installed

Disabling accent color from current wallpaper stops the behavior.

This was fixed for the case of full-screen video by not playing the transition effect for full-screen windows.

Still a (now more minor) issue for other things.

Just encountered this issue myself, running Arch Linux with KDE Plasma 5.27.8 on X11.

Since the original video link does not work any more, I recorded mine here: https://nc.felixf.eu/s/RKH9BYFf95QdLeo.
I am simply cycling back and forth between two wallpapers. You can also see my system load and a video running in the corner (firefox), which visibly stutters when the orange wallpaper is set. CPU load increases dramatically, even from applications like vorta (backup, not running) that should not be doing anything.

I am also using the "Use accent colour from current wallpaper" option, however it only happens on certain wallpapers (I use variety to cycle them on every reboot or manually like in the video). 
This is the wallpaper causing the issue: https://nc.felixf.eu/s/JnjJLZraiZCFCff
This one works fine: https://nc.felixf.eu/s/HzjaENc3RXq95oS

*** This bug has been marked as a duplicate of bug 467381 ***