Playing with a friend and suddenly it starts killing his "entity" and now cannot pick up items within the world.

Can you send the server's latest.log please.

you can find it here https://fabricmc.net/wiki/player:tutorials:logs_ml:windows

This release should fix that issue, a ticking player should be kicked instead of killed, but you will still have an underlying issue with the player that you will need to address as a ticking player is not good.

https://github.com/Bawnorton/Neruina/releases/tag/1.2.3