Sometimes projectiles pass through mobs. This bug seems to happen more at close range, and can seriously mess up both Survival and PvP.

This is a major bug that should absolutely be prioritized for the 1.16.4 update.

Video demonstration (happens at 0:32): https://www.youtube.com/watch?v=bdnqi0VzACY&feature=youtu.be

NOTE: Though this was tested on a realm against players I can confirm this happens with any entity even in single player