When the player blocks an incoming arrow from a skeleton with their shield, and the arrow is deflected into the skeleton's hitbox, the skeleton does not take damage from the delected arrow.
Steps to recreate:
Obtain a shield
Corner or trap a skeleton, allowing it to shoot at you
Get within 2 blocks of the skeleton hitbox
Block the skeleton's attack with your shield
The skeleton should take damage from its own arrow, but it does not
Cant confirm