Villagers have pathing issues with doors. When a villager opens a door and steps through, it immediately turns around, opens the door backup, and goes the other way. This leads to multiple villagers spending the entire night walking back and forth between multiple doors and getting stuck on all of them. This leaves them vulnerable to hostile npcs, and it's annoying as hell to listen to multiple doors constantly opening and closing. It's not difficult to replicate, but it does seem some villagers are more affected than others. The one I have isolated in the screenshots is a nitwit, but any villager can be affected.