Application Style settings section is flickering non-stop

Application Style settings section is flickering non-stop.

What else is broken?

And why isn't rebooting from snapshot helping me?

inxi in

Woah. Game graphics are slow. Must be a problem with NVidia driver.

OK how can I fix all this?

Have you tried restoring your computer to a previous state with Snapper?

Tried a restore from yesterday. KDE layout is still broken, and opening a Lutris game, it doesn't start WINE at all...

OK... fixed the titlebar buttons. Somehow games started working again (?) but the saved file seems corrupted and it crashes loading.

But the Application Style settings window flickering remains. I don't know whether something else is broken, and I'd like to know what could have caused this.

Could underclocking cause this kind of system issues? (set undervolt to the same value that was stable in Windows)

If I'm to guess, I think that what happened is that KDE crashed, and as a fail-safe feature, it automatically restored its settings to default, and that caused a chain reaction of other problems.

I have this issue as well. It looks like there's a bug in Mesa 21.3 affecting Intel GPUs that causes this flickering.