You have a plex pass though, so nothing changed for you - you just got all angry because you didn't read the email properly.
Your users are going to be much worse off now than they were, and you will absolutely lose a bunch of them who don't want to (or can't) have to connect to a VPN every time they want to stream from your library.
Bob your uncle will absolutely not use Tailscale to stream from Jellyfin, so Bob your uncle will no longer have access to OPs library.