Nvidia GSync causes mass screen flicker in x11 sessions on 21.10

[Andrew Wood]

Since moving from Ubuntu 21.04 to 21.10 (I did a fresh install, not upgrade) I can no longer run any games in full-screen mode, there is a mass flicker and a black screen.

I've found this problem can be mitigated in two ways;

1) Run the game in windowed mode
2) Turn off gsync via the nVidia settings app

Ordinarily I'd conclude this to be an nVidia problem, but I'm using the same driver version as I was on 21.04 so the major change has been the new Ubuntu version. I'm still using X11, not Wayland.

I'm using an RTX 3080 on a Samsung G7 Odyssey 32".

Happy to provide any logs or whatever people need, I'm a competent user but not that clued-in so will need to be told what to provide.