Yeah, I have issues with random really poor frame times. I'll be sitting at 144 FPS then get some frames that take 45ms to render each/severe stuttering.

I "fixed" it using the proton version of the game though I've heard some people say that doesn't work with match making... Haven't tried that yet.

I was thinking about trying the -vulkan launch option to see if that does anything if my proton install doesn't work.

EDIT: They were right ... VAC doesn't work via Proton. I retried playing the native version and it seemed to run fine this time with or without -vulkan ... so I'm not really sure what's going on anymore.

Maybe some things have been fixed either on the Linux/Mesa or on the Valve side.

I've had issues on stock x11 PopOS using nvidia. Decent fps, but bigger drops and frametime consistency seemed horrible. I have to turn off my (mismatched) 2nd monitor for my proper refresh rate to work, but it still looked very microstuttery. I miss VRR, but I think there's a bigger underlying issue than vsync/VRR not working. Haven't tried Wayland yet.

The game is set to run full screen ( as windowed fullscreen caps the framerate to 60, while the screen supports 144 ).

In case your game also doesn't launch on the main screen you can try setting the monitor to a different position on the virtual canvas:

https://github.com/ValveSoftware/csgo-osx-linux/issues/3282#issuecomment-1969271416

Fwiw, I've had no issues playing CS2 on either with my old (3700x/1080ti) or newer setup (5800X3D/7900XTX) with PopOS. The first doesn't seem too far away from your rig, have you tried switching the Nvidia driver you're on? I think Turing is fine with 560?

Did you install Steam via flatpak or normally?

I remember the frame time issue happening but it fixed itself and I can't remember the cause. Try changing the refresh rate of your monitor, it might kick something which fixes it.

Performance should definitely be mostly on par with Windows.