Created attachment 139820 [details] Screenshot SUMMARY Please see the screenshot. STEPS TO REPRODUCE 1. Log into a Wayland session with a 4k monitor (DP) and 200% scaling. 2. Attach a FullHD monitor (HDMI) and extend the screen. OBSERVED RESULT The 4k monitor's resolution changes to FullHD. EXPECTED RESULT The 4k monitor's resolution stays the same. SOFTWARE/OS VERSIONS Operating System: openSUSE Tumbleweed 20210629 KDE Plasma Version: 5.22.2 KDE Frameworks Version: 5.83.0 Qt Version: 5.15.2 Kernel Version: 5.12.13-1-default (64-bit) Graphics Platform: Wayland Graphics Processor: Radeon RX 580 Series ADDITIONAL NOTES You can see that KScreens' KCM has problems to display the full name of the monitor correctly within in the visualized monitor configuration.
When I changed the resolution back to 4k, KWin simply upscaled the image and it became blurry. First a re-login helped and solved the issue.
Sounds like you are affected by Bug 433460. For some reason, automatically-chosen scale factors need to be manually re-applied before they work properly. *** This bug has been marked as a duplicate of bug 433460 ***
(In reply to Nate Graham from comment #2) > Sounds like you are affected by Bug 433460. For some reason, > automatically-chosen scale factors need to be manually re-applied before > they work properly. I could confirm bug 433460 some other time, but I do not think it is the same -- at least for the symptoms. It's not the scaling, which changes, it's the resolution. If you look closely in the screenshot, the combobox says "1920x1080" but it should say "3840x2160". Or do you think it has the same root cause at least? If you think so, please feel free to mark it as duplicate again. Then, however, you should change the description [1] of the bug 433460 otherwise it doesn't match mine. [1] https://bugs.kde.org/show_bug.cgi?id=433460#c5 explains it probably rather good.
There's another difference, it's also not about going from X11 to Wayland, it all happens during the Wayland session.
I guess, this is obsolete now. :-)