Jellyfin is a media player. It’s built in security is more than enough for most. A lot use it for access to their own personal collections. You’re using it for your own use, you’re not distributing so doubtful anybody would care. There’s no way to know what’s there so not worth anybody’s time. Now if you were selling logins to that server and advertising the content then things would be different in the same way that if you seed pirated content they will care more than if you just leech it. For all they know you could have your personal home videos behind it or legitimate backups of physical disks you own. Hide it behind a subdomain and random path then unless somebody is looking for it they won’t stumble on it in the first place. This should be enough really. Jellyfin is designed to keep your content secure. The only way somebody official would come knocking is if they suspect there’s something to hide. Unless you tell people they have no reason to suspect. They have much bigger fish to fry.

I don’t think you have anything to worry about but you can ofc secure things further if you want to jump through a few mostly unrequired hoops.

That’s just my personal opinion. If you don’t feel safe exposing it then you shouldn’t and should setup a vpn or similar and hide it all behind that. My jellyfin has been exposed for years. Just me and my family using it. I’ve never had anybody try to access it. Nothing exciting behind it other than family videos but nobody knows that.