As you can see, there are two apps shown that come from Steam. But these apps have been deleted in the Finder. The storage is not used anywhere in her Application Support Steam folder (storage used there is 10GB, because of the Subnautica app only). Show in Finder does nothing and Delete... does nothing as well.
We would like to get Storage Management to give the correct info so we actually know if that is still in use storage or that it is just another display bug. We tried several things, including turning off TimeMachine and removing all local snapshots, running Repair from Disk Utility, reindex Spotlight, etc., but nothing so far has helped.
FileVault2 is active on the system.
This question is like this question from Sep 2019 (which did not get an answer so far) but with some more info on what we tried and with a fully up to date Catalina as per today. I can do technical things if people have suggestions, that might answer both questions. In both cases these were Steam apps, so there is a potential Steam on macOS issue here.