Some enemies, particularly Piglin Brutes, Vindicators and Slimes (both normal and Magma,) I have noticed are able to attack in an unbelievably rapid succession.

Piglin Brutes and Vindicators, since they have an axe, will disable your shield, however the damage is still blocked. But even if you do block it, they can literally attack again less than a tick afterwards, rendering blocking their hits completely useless, as they'll just immediately hit you again with no chance at all to move away, or push them back before the second attack. This doesn't make sense because, axes have a long cooldown for players, likely due to how heavy they are, players would never be able to double hit like that, or at least not without doing a lot less damage. Piglin Brutes and Vindicators however can double attack you in such a brokenly quick speed, AND do full damage. This is very unfair and completely lacks any sense at all.

Slimes and Magma Slimes can destroy a full durability shield in a matter of seconds when you block their hits, as they apply very rapid damage to the shield so quickly that it literally eats through the durability so insanely fast. This also is quite unfair and doesn't make any sense.