Bug 498679

Created attachment 177364 [details]
A picture taken of the primary monitor. Top is with >= 105% scaling on secondary monitor. Bottom is <= 95% scaling on secondary monitor. Notice the fuzzyness at the bottom parts of the text.

SUMMARY
When there are two monitors plugged in, one with scaling and one without, the monitor without scaling will have certain text be rendered blurry.

The scaling on the second monitor must be set to 105% or higher. Setting it to 100% or lower does not cause issues.

There are a couple of places where it's very noticeable:
- The categories in the application launcher.
- Some applications will have a blurry name in the application launcher (Contact Theme Editor and Contact Print Theme Editor).
- The text under "Display Configuration" (Settings -> Display & Monitor) where it mentions "Legacy applications (X11)".
- Gitlab in Google Chrome (https://gitlab.com/CalcProgrammer1/OpenRGB). This requires fontations font backend to be enabled (chrome://flags/#enable-fontations-backend), this is turned on by default in Google Chrome 132.0.6834.83.

STEPS TO REPRODUCE
1. Start a Wayland session.
2. Plug in two monitors.
3. Set primary monitor to 100% scaling .
4. Set secondary monitor to 105% or higher scaling.
5. Logout and login or reboot the machine.

OBSERVED RESULT
Certain text will now be rendered blurry on the primary monitor (100% scaling). 

EXPECTED RESULT
Text on the main monitor should look as sharp as when having 100% or lower scaling on the second monitor. 

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Fedora Linux 41
KDE Plasma Version: 6.2.5
KDE Frameworks Version: 6.10.0
Qt Version: 6.8.1

ADDITIONAL INFORMATION
I can also reproduce this problem on Arch Linux with KDE Plasma from the unstable repository (6.2.90-1). Primary monitor is 2560x1440 and secondary monitor is 3840x2160. Orientation of the secondary monitor does not make a difference.