All of the things others have said are excellent points, I would also like to point out that if you go to the steam hardware survey and select Linux only you'll see that Arch is the most used distro (after SteamOS), and that was also the case when the Steam Deck was announced in July 2021 https://web.archive.org/web/20220806051441/https://store.steampowered.com/hwsurvey/

And from my personal experience there's a reason for that, other than the I use Arch btw meme, despite most ports having Ubuntu in mind, and despite Ubuntu being the more user friendly distro, games just work on Arch. It's a weird thing where gaming on all of my arch machines is very painless, but gaming on the Ubuntu ones is frustrating, there's always something not right, it feels like the machine is chugging, or the driver decides not to work, or the game shows a black screen, or prime decides not today, etc, etc. I admit this is personal experience, and others might have the exact opposite, and that this is kind of biased because as a general rule people who use Arch tend to be more knowledgeable about Linux than people who use Ubuntu, but from replying on several Linux forums it's generally people with Ubuntu that have problems with games and people with Arch usually report that "it just works" for them.