UE 5.3 game fullscreen problem after conversion from UE 5.21

[filanek]

Hello,
I am not sure if this is UE 5.3 problem or my ignorance, this happens after conversion from ue 5.21 to 5.3. My screen resolution is set to 3840x2160, my game resolution is set to 2560x1440 fullscreen (f Set Fullscreen Mode = Fullscreen) button, rollout menu combo (f Set Screen Resolution). The mouse cursor xy is still like in true fullscreen mode. Any advice please?

[filanek]

r.SetRes 2560x1440w - works ok
r.SetRes 2560x1440wf - is fullscreen windowed but does not change/scale the resolution (it uses always screen full resolution 3840x2160 in any command resolution case)
r.SetRes 2560x1440f - broken fullscreen changes the resolution, but occupies just top left corner of the screen without the resolution scaling (as in the image in my first message)

when compiled this happens with the default project files as well

[filanek]

I have three GPUs and three screens connected to the first GPU.
My r.GraphicsAdapter was set to 1, when I set this to 0 (the main display GPU) “my ignorance problem” seems solved.