Hi. What are this mixins used for? :I
PlayerEntityMixin
LootableContainerBlockEntityMixin

PlayerEntityMixin is there to solve desyncs caused by server-side dismounting not being respected because the player is still mounted on the client side

LootableContainerBlockEntityMixin allows opening chests from any distance while using a certain item (although I'm not super happy with it and I'm probably going to be removing that item and everything associated with it soon)