GP isn't saying that Linux is faster than Windows; they are saying that a Windows app running under Proton under Linux is faster than a native Linux app running under Linux.
I highly recommend tweaking things like Proton versions (try GloriousEggroll for example). I've been playing OW and OW2 on Linux for years, had very few issues since the beginning and excellent framerates.
I have a notebook (Nvidia 10xx something gpu), 8th gen intel I think. It gets plenty warm playing games, but the games play fine on PopOS. The fact that they run is pretty great.
But I think of the steam deck which is basically a Linux PC. Its lowerer spec, low power, but it seems to run pretty well without terrible battery life.
I tried Overwatch 2 with Proton and performance was abysmal. My computer seemed to be melting and FPS was jumping all over the place.
It does 144fps on Windows 11 without sweating (same PC).