I know there have been many versions of this, but I think I should add something:

This happens when:
-2 or more villagers are on the same side of the door

-At least 1 villager on each side of the door

-When a bell rings

_When in 1 block thin spaces

Something also unusual, when you have 2 doors facing outwards in a 90-degree angle, villagers cannot sense this and sometimes you have to open the doors for them, causing them to spam for a bit and then walk away, even if something important is in the house like a work station or a bed.