You can either navigate all the dark patterns Plex has put and will put in the way to force you to pay, or you can simply install Jellyfin and ditch Plex. I did the last.
I have a smallish 100TB library I'd really love to move away from Plex, I regularly test out Jellyfin to see if they've finally made it usable. But sadly Jellyfin is still very far from being a good Plex replacement, it's just janky as fuck.
Constant playback errors, terrible client support, significantly higher resource usage.
I still think Jellyfin is interesting and I'm going to keep it running alongside Plex to trial it.