Cyberpunk’s performance was awful for everyone at launch, Windows, Linux and consoles.
But it wasn’t? There were a lot of bugs, to be sure, but PC performance was not among them. Hell, I was on a 970 at the time, and it was still fine.
The console versions specifically were a shit show.
But in regards to running better on Linux, a lot of it tends to come down to shader precaching. Lots of stutters on Windows are the first time a shader loads. That was definitely the case with Elden Ring.