Whenever I jump up and down the game's framerate drops to 30-40 (previously 165+). Did some testing and other mods do seem to effect the number, but not by much (example, with 20 mods installed, FPS drops to 25, with 0 (other than fabric api and xaero's map mods) it drops to 60)

Version: 1.20.1
Mods: Tested with and without various mods

If you want to investigate further on your side I recommend using Spark or VisualVM to capture a profile during the lag.

I can't reproduce this and there is nothing in XaeroPlus that does anything on jump events.

Personally I think it might be something to do with the map switching between 2 y levels. I didn't properly show it in the video but at 13 seconds in the video the map is briefly visible. Although, if you're unable to reproduce it, that's good I guess.