You should not get a false positive on a specific malware. Agent Tesla variants are keyloggers and credential stealing malware. And itch does scan files they host. I doubt they would not scan simple zip files.
The game was updated a while ago, so you should have gotten the false positive both times. If it were a false positive.
Unless a freak coincidence resulted in a one time false positive, I would be worried, that the Agent was or is active at your home system and was accidentally detected. A quick read told me, that at least one variant can deinstall itself. I would assume it does this, if some credentials were stolen, so the user does not notice the theft and changes the credentials.