Expected Behavior:

Mob is dismounted to an adjacent block from the cart

Observed Behavior: 

Mob is ejected inside the cart

Steps to reproduce:

1. Launch version 1.21 Pre Release 2, put a creeper in a minecart kill the cart and see where the creeper is put after killing the cart.

2. Launch version 1.20.2 or below and repeat the same steps and see the creeper goes to different positions

Results of the bug:

This breaks almost all cart based contraptions like villager based trading halls, cannons, and mobs farms.