Do you not do any renaming? That probably would make it even easier as you can just brute force with a database of filenames scraped from torrents. I already have a proof of concept that generates valid jellyfin IDs from any given file path, it only takes a few more steps before you can plug in a shodan scan of jellyfin instances and just shotgun a bunch of IDs generated from torrents.csv at them and find stuff you can stream without authentication.
People not bothering to rename, using the default radarr naming scheme, or everyone using the same naming pattern from trash guides just makes it easier.
Probably the only way to guarantee nobody can probe your media and stream it without authentication is to make sure to rename everything using a format that only you use or mount all your media under a path inside docker that contains a long randomly generated folder prefix.