Some games seem to become corrupt for unknown reasons. It’s possible that there is a bad area on the hard disk or SSD or there is some updates that does not update the catalogs.

To verify a game, right click on the game and select properties. Then chose local files. Small games are not a big problem. Games like Grand Theft Auto V are much larger,.

The verification will show up in the downloads. Steam will automatically download and part that is damaged automatically.