Bug 511676

Summary:	Night Light transition causes visual glitches only while second monitor is on
Product:	[Plasma] kwin	Reporter:	kdalias.njre2
Component:	night color	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED WORKSFORME
Severity:	minor	CC:	xaver.hugl
Priority:	NOR
Version First Reported In:	6.4.4
Target Milestone:	---
Platform:	EndeavourOS
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	Visual glitching when transitioning from/to Night Light mode

Description kdalias.njre2 2025-11-05 14:51:03 UTC

SUMMARY
Transitioning from/to Night Light mode causes visual glitches on one of my monitors only when both are on during the transition. I'm currently on Plasma 6.4.5, but the issue is still there on 6.5. I hadn't encountered the issue up to 6.3.5, I updated directly to 6.4.4 which was the first version I saw it, so it may have been introduced earlier than that.

STEPS TO REPRODUCE
1. Enable/Disable Night Light OR Wait for automatic transition

OBSERVED RESULT
Visual glitches on screen during transition

EXPECTED RESULT
Transition without visual glitches

SOFTWARE/OS VERSIONS
Operating System: EndeavourOS
KDE Plasma Version: 6.4.5
KDE Frameworks Version: 6.19.0
Qt Version: 6.10.0
Kernel Version: 6.16.10-zen1-1-zen (64-bit) (Same behavior on 6.17.7-arch1-1 (64-bit) too)
Graphics Platform: Wayland

ADDITIONAL INFORMATION
Processors: 16 × AMD Ryzen 7 7700X 8-Core Processor
Memory: 32 GiB of RAM (30.9 GiB usable)
Graphics Processor: AMD Radeon RX 6700 XT

Also, I tried to replicate the issue under the same conditions in the following Live ISOs in my system but without success:
- EndeavourOS Mercury (Plasma 6.2.5)
- Manjaro 251013 KDE minimal (Plasma 6.3.6)
- KDE Neon 251030 (Plasma 6.5.1)
and also on my up-to-date laptop also without success:
  Operating System: EndeavourOS
  KDE Plasma Version: 6.5.1
  KDE Frameworks Version: 6.19.0
  Qt Version: 6.10.0
  Kernel Version: 6.17.7-arch1-1 (64-bit)
  Graphics Platform: Wayland
  Processors: 16 × AMD Ryzen 7 4800H with Radeon Graphics
  Memory: 32 GiB of RAM (29.3 GiB usable)
  Graphics Processor: AMD Radeon Graphics

Comment 1 kdalias.njre2 2025-11-05 14:56:10 UTC

Created attachment 186521 [details]
Visual glitching when transitioning from/to Night Light mode

Only happens when second monitor is on

Comment 2 Zamundaaa 2025-11-06 21:18:40 UTC

Please temporarily set the "color accuracy" display setting to "prefer color accuracy" to prevent KWin from using the kms lut for night light, and test this again. Does it go away, or at least change?

Comment 3 kdalias.njre2 2025-11-08 13:38:34 UTC

(In reply to Zamundaaa from comment #2)
> Please temporarily set the "color accuracy" display setting to "prefer color
> accuracy" to prevent KWin from using the kms lut for night light, and test
> this again. Does it go away, or at least change?

Sorry for the late response, changed both monitors to "Prefer Color Accuracy" and I haven't seen any glitching from a few quick tests so far, so hopefully that was the cause. Thanks for the help!

Comment 4 Bug Janitor Service 2025-11-23 03:46:36 UTC

🐛🧹 ⚠️ This bug has been in NEEDSINFO status with no change for at least 15 days. Please provide the requested information, then set the bug status to REPORTED. If there is no change for at least 30 days, it will be automatically closed as RESOLVED WORKSFORME.

For more information about our bug triaging procedures, please read https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging.

Thank you for helping us make KDE software even better for everyone!

Comment 5 Bug Janitor Service 2025-12-08 03:45:59 UTC

🐛🧹 This bug has been in NEEDSINFO status with no change for at least 30 days. Closing as RESOLVED WORKSFORME.