The bug
Villagers will wake up within random moments of the night to seek out a new bed to sleep in. Once they find it, they completely change their home, making it harder to keep villagers next to their correct job site blocks.
This event, however, only happens when the house they live in is 2 blocks tall (the height of the player and the villager). If it is 3 high or more, this problem does not exist.
Confirmed in 20w19a.
Even tho Mojang fixed MC-152084 in the most recent Snapshot, this problem can still happen under the same circumstances you specified in this Ticket, so for testing try to place a Bed for a Villager in a 2 Block High House (Making sure the roof it’s very close to the Players/Villagers head) eventually during the night time the Villager sleeping here will get kicked off and automatically count this Bed as Invalid and so on it will seek for a different one, but after a while if it didn’t reach another Bed it will come back to this one and it will keep reproducing this Issue constantly.