Jellyfin deleted 2.5tb of my personal data without prompt or asking.

[TheDreadPirate]

One of the points presented in this thread on why OP lost his media is because they possibly told Jellyfin that their media folder(s) were cache folders.
Cache is considered safe to destroy as long as the original files the cache was derived from still exist. You can always recreate it.

IIRC, the OP put their cache directory at or above the directory their media was in to try to troubleshoot some permissions issue.  So when the scheduled job to recursively clear the cache ran it also deleted their media.