Depending on your server, and how you install you might have a bad experience. I’ve had issues where it wasn’t finding the film/series metadata, having plugin issues, and being incredibly slow (slow UI when anything is being done, slow scanning folders, slow loading saved metadata, etc). Jellyfin, like a lot of open source software, feels like jank. The devs know about a lot of issues, but they’re swamped with so much, with this big of a project.
People criticise Plex, rightfully so with some of their bad decisions, but it still works better. For me, Plex runs so much better, and without issues. I won’t be moving away to Jellyfin in the foreseeable future, but I’ll be glad when I am able to.
Cloudflare is a decent service, with really good security. Plus, with their tunnelling feature, they’re helping to keep you private. If you just pointed your A record to your IP, that’d be visible to everyone. Instead, your A record is just visible to Cloudflare. Plus it’s handy if you’re using them to forward a bunch of services onto the net. Not to mention all the other security features you can use. DNS records by design, are not private.