Steps to reproduce

1. Trap a blaze inside a room with no ceiling.
2. From the outside of the room make a hole in a wall of the room at foot height and hit the blaze through the hole, then fill the hole again.
3. Climb up to an elevation higher than the walls of the room, but don't move close enough to see down into the room.

Expected result

The blaze does not follow you because it cannot see you.

Observed result

The blaze flies up out of the room and attacks.

Impact

If the room is a trident killer, blazes will fly up and fail to be hit by the tridents whenever the player is at a higher elevation than the floor.

Blazes are able to track players through walls and match their Y coordinate. As far as I can tell, blazes should only try to match a player's Y coordinate when they see a player, being able to tell where they are through a wall makes no sense.