I’ve got a 4070ti running most recent nvidia-open on arch and haven’t had that happen, but I don’t tend to run with vsync often.
What proton version are you running this on? Had some weird almost microstutters in cutscenes playing DA:Veilguard through moonlight on my steamdeck. Swapping to experimental resolved that, think it was one version of proton-ge that I had the issue with.
Do you have vrr enabled by any chance?
Are you running through gamescope? Have had grief with gamescope and nvidia, but that was mostly with hdr.
Another crab’s treasure was fantastic, been loving Nine Sols as well and it might be my favourite game visually, lots of hand drawn stuff and it blends Cyberpunk with Eastern mythology (devs describe as “taopunk”)