Wan Movie Streaming, fraction of available.

[TheDreadPirate]

There's also the round trip time.  When you do the speed test it is using a local to the exit node speedtest server.  But for your jellyfin data it has a much longer round trip time since it has to go to wherever the exit node is before coming back to you.

If you have the option to select your exit node, pick one closer to you and see how it goes.