A security vulnerability found in the Unity engine, which had laid dormant for almost a decade, was recently patched. Games made using the engine also need to be patched, however, so expect a lot of games you wouldn't expect to still be receiving updates to suddenly download one out of the blue. Overcooked 2, for instance.
Microsoft, which owns so many videogame studios it's hard to keep track, has announced that some of its games will be temporarily pulled from storefronts while patches for the vulnerability are worked on. Which is why, if you look for Fallout Shelter, Pentiment, Wasteland Remastered, or Wasteland 3 on the Steam store right now you won't find them. If you own them already you still have access to them, though Microsoft suggests you "should temporarily uninstall the app."
Even games that weren't made in Unity have been affected if their companion apps and artbook launchers, the kind you often get in deluxe editions, were. Avowed, for instance, which was developed in Unreal Engine 5, has a digital artbook that's a Unity app.
It's worth noting that the security vulnerability in question hasn't actually affected anyone yet. As Unity explained, while programs made in Unity are "susceptible to an unsafe file loading and local file inclusion attack depending on the operating system", malicious files would need to be present on your device already, and "Code execution would be confined to the privilege level of the vulnerable application," which would only be a problem if you were running games as an admin. It's still worth fixing obviously, and it's been taken seriously by plenty of folks.
As soon as Pentiment's back on Steam you should check it out, by the way. It's a brilliant murder mystery.
