Im not sure where to go with this issue. Or what is causing it, but I think its either KDE or an Nvidia problem. The problem started around Christmas, when VRR and new drivers and all that came out. I saw another user also had this issue around that time in discord chat for CachyOs.
I have an Nvidia RTX 4090, and 2x 4k screens.
The monitor im using is an PG42UQ, and it`s 120hz by default. It supports an OC that makes the screen go up to 138hz.
When I activate the 138hz, all fullscreen aplications makes the screen turn black for 2-4 seconds after exiting fullscreen. Then it comes back again. Like if I close youtube in fullscreen is an example to it. This is to everything that has an fullscreen.
This issue is not there, if I put my screen on 120hz automatic adaptive sync.
I tested 2 browsers, Brave and Firefox. Same issue on both.
But if I turn off adaptive sync to never on 138hz, the black screen goes away.
If I swap between 120hz and 138hz, my system hard crashes, so I need to push the reset button and reboot.
For me, its like it struggle to detect my hz in a way. After swapping to 120hz, it also detect my screen as an ultrawide, so i need to change it too 16:9.
Been so many major update past months, that I cant pinpoint what is causing the issue.
Had a new hard crash. So tried logging that as well under the nvidia-bug.report1.log.gz
nvidia-bug-report.log.gz (1.4 MB)
nvidia-bug-report1.log.gz (827.6 KB)
I see more people struggle with this for some reason now in the community. I linked my post and some people comming forward with the same issues.