On top of that, the 4090 may be 25% better than the 7900 XTX - but it's also 50+% more expensive than the 7900 XTX, which is a pattern which can be seen for every generation and version of GPUs by Nvidia/AMD. Nvidia's equivalents to AMD's cards are generally 25-50% more expensive, with worse performance but better Raytracing and of course DLSS support - oh wait, DLSS 1 and 2 are only for RTX 20 and up, while DLSS 4 is only for 40 Series GPUs. Which means no matter how good it looks, FSR will be the only alternative for almost all players, even those using NVidia cards like me.
Something different: Intel's Arc GPUs would maybe be worth a shot. According to a PC World article, the A770 beats the 3060 even in it's own habitat - Raytracing. It's cheap and gets better with every driver update. It also seems like the Arc GPUs are compatible with Linux fine, though I'd suggest you look up the compatibility with the games you want to play.
I have a 1070 Ti, but I'm on Ubuntu and I haven't had any issues at all for ~5 years. IMO the issue then is Arch, and how the drivers are handled. I also have only updated the driver once (450-server to 525-server), when Satisfactory switched to unreal engine 5.
I would still recommend AMD though, and I also plan on switching when I have the money for it.
I have a 1060 on Arch and had no problems whatsoever. It will get ugly once the 1060 is no longer supported by the mainline driver, though.
Yup. It's getting to be fairly old GPU, I'm feeling anxious about getting a new one because I'm poor af but... ¯\_(ツ)_/¯