Wrong resolution setting when Wayland fractional scaling is enabled

[simonioc]

I've only tried with sdl2-compat since few games use SDL3 already, but i think it's a SDL3 problem because it doesn't happen on X11.

Reproduce steps:
Pick a game and set it to wayland while running on a fractional scaling session (KWin does support it), for example Super Meat Boy.
The game either doesn't display anything or the resolution does not match the monitor's one and it can't set into it.
It looks like SDL_GetDisplayMode() gets them correctly but SDL can't actually set them.
Also i don't know whether this is a SDL or KWin problem, i can say glfw games do not currently have this problem on the same Wayland session.

[simonioc]

also windows get resized, this may be intentional but it breaks things i think