Included is the following disclaimer by the author:

• This may not be representative of all types of Linux users. I’m sure this is not what your AWS engineer uses on EC2.
• This may not be completely representative of all Linux gamers either. But I’d wage this is actually a good predictor where the market is going to shift. We saw first that Manjaro was getting the boot here first, before going under pretty much everywhere.
• There may be some additional biases, due to whoever used ProtonDB.
• Flatpak is NOT a distro, but that’s what Steam reports when it’s running on Flatpak, and Flatpak being distro independent we report it as a separate environment, if that makes sense. Feel free to ignore it if you wish.
• Arch Linux is Arch Linux on desktop. The Steam Deck’s OS is reported as HoloISO, not Arch Linux, so stop trying to claim that Arch is first because of the Steam Deck! This is mainly data reported from desktop PCs, so no, SteamOS is not a thing at the moment on such machines. This may change as Valve starts providing official support beyond the Steam Deck.