Switching from 20w06a to 20w07a causes all villagers in a pre-existing village to disappear. Additionally, if they were in beds when the save file was closed in 20w06a, opening the save in 20w07a and attempting to sleep in the bed will result in the message that the bed is occupied, despite no entity sleeping in it. Destroying and replacing the bed will allow the player to sleep in it, though the villager will not appear.

Thank god I backed up my save.