I'm so confused by this common sentiment in the community. I've been gaming on Arch / NixOS for the past several months with an NVIDIA card after I switched earlier this year. Basically no issues.
Meanwhile, my buddy converted to Manjaro, and has a Radeon. He's been having awful issues. Several of the games he plays crash constantly, especially if they are multiplayer. He tried switching to openSUSE recently; no real improvements.
I wanted to buy AMD for my eventual next card, but now I'm terrified of doing so, and deeply confused why everyone says AMD is better for Linux.