Something I never fully understood with file versioning is on which side to apply it. The source or the receiving end?

In Qbittorrent you can tell it to not download certain files. So you can tell it to ignore anything with *arj, for example.

I’ve had this happen with people pretending to be certain groups and making the file a .lnk (a link to a website, I assume). Sonarr will still send the file to Qbittorrent, but it won’t get downloaded at all.