Apple Arcade game has disappeared from iPad and appears as if never downloaded

We all would freak after losing months of game data - but my son is autistic and Bloons Tower Defence 6 on Apple Arcade is what regulates him. It’s suddenly disappeared from his iPad.

When we went to re-download it, instead of the little cloud that allows you to download it again, we found the usual “GET” button - as if he’d never downloaded the game at all. There is absolutely no save data associated with his account, as far as we can tell.

Has anyone seen anything like this at all before? Is this just what happens if an Arcade game gets deleted?

Please help if you can give any advice at all. This poor child is devastated and I’m good with tech stuff but I’m completely stumped on this one. TIA