Timothée Besset, a software engineer who works on the Steam client for Valve, took to Mastodon this week to reveal: “Valve is seeing an increasing number of bug reports for issues caused by Canonical’s repackaging of the Steam client through snap”.
“We are not involved with the snap repackaging. It has a lot of issues”, Besset adds, noting that “the best way to install Steam on Debian and derivative operating systems is to […] use the official .deb”.
Those who don’t want to use the official Deb package are instead asked to ‘consider the Flatpak version’ — though like Canonical’s Steam snap the Steam Flatpak is also unofficial, and no directly supported by Valve.
As far as I know, SteamOS is already based on Debian. The dev is complaining about users trying to install steam on their own Ubuntu installs, not SteamOS.
EDIT: nvm, it used to be Debian, but the newer versions for steamdeck are based on Arch. Apparently they wanted rolling updates so that it would be easier to push out changes more frequently.