Created attachment 183480 [details]
The game when started in fullscreen with 125% scaling

After upgrading to Plasma 6.4, when using Wayland, I started having a problem where some games that run natively on Linux display weirdly in fullscreen, more precisely the game window shows up at the left side with the rest of the fullscreen window being black. This doesn't happen if I scale the screen to 100%, then start the game, after which I could set the scaling back to the desired value above 100% to work around the problem completely. I would prefer not to have to do this as 100% scaling is too small for me on my 1440p monitor.

Steps to reproduce:
1. Enable fractional scaling in Plasma 6.4.0 or later
2. Open a Linux-native game in fullscreen which is affected by this issue(doesn't seem to happen with all games)

Observed result:
The game opens, but the window displays smaller and on the left side of the screen.

Expected result:
The game displays on the entire screen.

Software/ OS versions:
Linux: Fedora 42 kernel 6.15.7
KDE Plasma Version: 6.4.0
KDE Frameworks Version:  6.16.0
Qt Version: 6.9.1

Additional information:
Unlike in the previous versions of Plasma, the same game runs natively on Wayland instead of through XWayland and can't be forced to run through XWayland(as trying to do so results in the game failing to launch).