There's a bit of unfortunate drama going on right now in Steam Deck land, with the Steam Deck plugin NonSteamLaunchers for Decky Loader getting the boot.
Nobody should ever be banned without knowing exactly what they were banned for. Either he's lying (I doubt it) or they didn't bother telling him, just gave him a perma ban without notice.
That's pretty shitty. They deserve the shit storm this will kick up.