Nah, setting non-standard ports is sound advice in security circles.
People misunderstand the “no security through obscurity” phrase. If you build security as a chain, where the chain is only as good as the weakest link, then it’s bad. But if you build security in layers, like a castle, then it can only help. It’s OK for a layer to be weak when there are other layers behind it.
Even better, non-standard ports will make 99% of threats go away. They automate scans that are just looking for anything they can break. If they don’t see the open ports, they move on. Won’t stop a determined attacker, of course, but that’s what other layers are for.
As long as there’s real security otherwise (TLS, good passwords, etc), it’s fine.
If anyone says “that’s a false sense of security”, ignore them. They’ve replaced thinking with a cliche.
Specifically these issues: https://github.com/jellyfin/jellyfin/issues/5415
The big one is that video/audio playing endpoints can be used without authentication. However, you have to guess a UUID. If Jellyfin is using UUIDv4 (fully random), then this shouldn’t be an issue; the search space is too big. However, many of the other types of UUIDs could hypothetically be enumerated through brute force. I’m not sure what Jellyfin uses for UUIDs.