Zombies can only track villagers if they see their head. If zombies see only a villagers feet, they will not pursue them and villagers will not panic
MC-187805
Zombies/drowned not tracking villagers when they can only see their feet
Resolved
Invalid
1
There used to be a bug where zombies trying to pathfind to impossible locations would cause lag, MC-17630 - this was fixed, hence they do no longer try to track them to impossible locations.