Zombies can only jump up blocks halfway underwater
When a zombie is underwater and a player is in water or above land the zombie will try and jump up blocks to get to the player but it will only jump up halfway preventing it from getting over the block.
Created Issue:
Zombies can only jump up blocks halfway underwater.
When a zombie is underwater and a player is in water the zombie will try and jump up blocks to get to the player but it will only jump up halfway preventing it from getting over the block.
When a zombie is underwater and a player is in water or above land the zombie will try and jump up blocks to get to the player but it will only jump up halfway preventing it from getting over the block.
Zombies can only jump up blocks halfway underwater.
Zombie pigmen, wither skeletons, and zoglins try to get out of the lava by jumping over blocks, but they can't because the lava slows them down vertically and causes them to jump too low. This exact problem occurred with zombies in water after the release of 1.13: MC-129601

Still an issue in 18w20a
Can confirm for 18w21b
Cannot reproduce in 1.13.1. Can someone please check if this is fixed.
Couldn't reproduce either.