I use OpenSuSE Tumbleweed. Up to date packages but with relatively good stability due to how they're tested. Rolling release distros are always more risky, but for gaming you probably do want up to date packages to ensure graphics drivers and bleeding edge versions of Proton, Vulkan and even Wine work as expected. I think that's most true for newer games and those where you may need to use Proton Experimental. Its also a good broad distro for other uses, rather than solely focused on one element like gaming.

Steam Deck is based on Arch; it's not quite rolling release but they do relatively frequent updates to their version of Linux so a rolling release distro is probably going to be closer to it than most annual release and certainly LTS released linuxes.

Nobara is also a good distro to consider. It's made by the guy who game up with Proton-GE and is gaming focused. It's also rolling released and optimised more for gaming including the kernel. I use it on a living room PC for the past 5-6 months and like it so far.