Possibly the same root cause as Bug 428357.

I can reproduce this bug under Manjaro using plasma version 5.26.5-1. It also started around the time that this bug was reported.

The bug persist in 5.27.4-1 on Archlinux.

When laptop left locked over night on morning unlock it keeps night colour.

When time for night colour is reached, it set up colour to day colour as an instant (that blue flash hurts my eyes) and slowly transiting to normal night colour.

Also showed up on Endeavour OS a couple months ago.

I don't think it's the same bug as https://bugs.kde.org/show_bug.cgi?id=428357, since the bug here is that the state of night color is mismatched with the state of the actual colour of the monitors, and stays that way.

An example of something that will fix this condition for one monitor is to unplug it and plug it back in, or change the resolution.

Also, making it preview a different colour temperature then disable the preview will rectify it across all screens.

Reproduced on KWin Wayland 5.27.5 on Arch Linux, with AMD Mesa drivers. I believe that this is a wayland only bug since it did not appear to happen on X11 when I was still on X11, but occurs on the same system with the same software version on wayland.

Poking the preview can be achieved with a script like so:

#!/bin/sh

busctl call --user org.kde.KWin /ColorCorrect org.kde.kwin.ColorCorrect preview u 5000
sleep 1
busctl call --user org.kde.KWin /ColorCorrect org.kde.kwin.ColorCorrect stopPreview

Wow, I have an almost identical script!

$ cat ~/bin/fix-kwin-color.sh
#!/usr/bin/env bash
qdbus-qt5 org.kde.KWin /ColorCorrect org.kde.kwin.ColorCorrect.preview 4000
sleep 5s
qdbus-qt5 org.kde.KWin /ColorCorrect org.kde.kwin.ColorCorrect.stopPreview

Looks like this might be the same problem as described in https://bugs.kde.org/show_bug.cgi?id=468295. WDYT?

(In reply to Ilya Bizyaev from comment #6)
> Looks like this might be the same problem as described in
> https://bugs.kde.org/show_bug.cgi?id=468295. WDYT?

It sounds reasonable for me.
I think main reasons are:
* night-to-day transition doesn't occurs for some reason
* day-to-night transition doesn't calculate real transition, but forces start point at instant

Another thought I have is there's another bug that I sometimes experience in which the monitor brightness gets desynchronized after monitors dim for sleep warning: is this a general DDC/DPMS handling bug where the monitor's state gets out of sync?

Can you please post the output of `qdbus org.kde.KWin /ColorCorrect GetAll org.kde.kwin.ColorCorrect` when screen color temperature is incorrect? Please also specify the expected screen temperature

.

$ qdbus org.kde.KWin /ColorCorrect GetAll org.kde.kwin.ColorCorrect
available: true
currentTemperature: 6500
enabled: true
inhibited: false
mode: 0
previousTransitionDateTime: 1690281092
previousTransitionDuration: 2936755
running: true
scheduledTransitionDateTime: 1690334696
scheduledTransitionDuration: 2936755
targetTemperature: 6500

Operating System: Fedora Linux 38
KDE Plasma Version: 5.27.6
KDE Frameworks Version: 5.108.0
Qt Version: 5.15.10
Kernel Version: 6.4.4-200.fc38.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 4 × Intel® Core™ i7-5600U CPU @ 2.60GHz
Memory: 11.5 GiB of RAM
Graphics Processor: Mesa Intel® HD Graphics 5500
Manufacturer: LENOVO
Product Name: 20BX001FUS
System Version: ThinkPad T450s

This also happens when the screens are off, for example:
1. Lock the session at 5PM and press escape to turn off the screens, not putting the computer to sleep (temperature is 6500K)
2. Wake up the screens at 12AM (temperature should be 3900K)

The target temperature is not applied at this point, however this is the output of the qdbus command:
$ qdbus org.kde.KWin /ColorCorrect GetAll org.kde.kwin.ColorCorrect
available: true
currentTemperature: 3900
enabled: true
inhibited: false
mode: 1
previousTransitionDateTime: 1690572475
previousTransitionDuration: 3351000
running: true
scheduledTransitionDateTime: 1690603343
scheduledTransitionDuration: 3337175
targetTemperature: 3900

Clicking the applet twice works to fix this case.

*** Bug 468295 has been marked as a duplicate of this bug. ***

*** Bug 462672 has been marked as a duplicate of this bug. ***

A possibly relevant merge request was started @ https://invent.kde.org/plasma/kwin/-/merge_requests/4286

Git commit befb50ebece843e6223d59577a9e1644704ba6c1 by Xaver Hugl.
Committed on 03/08/2023 at 12:46.
Pushed by zamundaaa into branch 'master'.

backends/drm: allow modesets with atomic tests if a modeset is already pending

Otherwise the tests will always fail

M  +10   -0    src/backends/drm/drm_pipeline.cpp

https://invent.kde.org/plasma/kwin/-/commit/befb50ebece843e6223d59577a9e1644704ba6c1

Git commit c580f8ed516c6c93d1e0a91cd96837744badd25e by Xaver Hugl.
Committed on 03/08/2023 at 14:59.
Pushed by zamundaaa into branch 'Plasma/5.27'.

backends/drm: allow modesets with atomic tests if a modeset is already pending

Otherwise the tests will always fail
(cherry picked from commit befb50ebece843e6223d59577a9e1644704ba6c1)

M  +10   -0    src/backends/drm/drm_pipeline.cpp

https://invent.kde.org/plasma/kwin/-/commit/c580f8ed516c6c93d1e0a91cd96837744badd25e

(In reply to kde from comment #12)
> This also happens when the screens are off, for example:
> 1. Lock the session at 5PM and press escape to turn off the screens, not
> putting the computer to sleep (temperature is 6500K)
> 2. Wake up the screens at 12AM (temperature should be 3900K)

This might be a completely separate issue as I am seeing this behavior still on kwin_x11 version 5.27.9.

Ah (In reply to Teemu Rytilahti from comment #18)
> (In reply to kde from comment #12)
> > This also happens when the screens are off, for example:
> > 1. Lock the session at 5PM and press escape to turn off the screens, not
> > putting the computer to sleep (temperature is 6500K)
> > 2. Wake up the screens at 12AM (temperature should be 3900K)
> 
> This might be a completely separate issue as I am seeing this behavior still
> on kwin_x11 version 5.27.9.

Ah correction, I see it after reboot, not after wakup from sleep, was redirected here from another issue