When a zombie variant breaks a door, it should show the break particles on both door blocks but it only shows it on the bottom door block. The cause of this issue is in the BreakBlockGoal class in the tick method right around where the door block is removed. First the door block is removed, then the level event of 2001 is sent to clients using the blockstate at the door's position. Problem is that the door block has already been cleared, so the block state id that is sent in the level event is 0 (air).

Simple to reproduce, just set difficulty to hard, lock a villager behind a door, spawn some zombies that can break doors, and observe a door break.