(yet) tl;dr In a recent thread on Mastodon, it was revealed that Ubuntu 23.04 users can’t install the Steam deb package from the Ubuntu archive without jumping through some technical hoops. It turns out this was a mistake, a bug was filed, and future builds shouldn’t have this problem. It’s not immediately apparent whether the (currently ‘broken’) ISO images for Ubuntu 23.04 will be rebuilt (unlikely) or if this will stay broken in 23.