Villagers refusing to sleep

Villagers have somehow "unclaimed" their bed or refuse to use it at night time. I am getting this issue in an iron farm I made. It has been working for the last 2 months perfectly, yet i noticed it stopped producing iron. after looking int othis i noticed the villagers in their cubicles weren't sleeping anymore. I had changed nothing about the design, version, mods or anything in the area. I have built no exploit/bug related farms that could possibly mess up anything in the game, purely vanilla non-bug farms.

Fixed by
Replacing the bed (Incredibly tedious with over80 villagers in their respective cells)

Recreate

I have been unable to recreate the scenario, and the iron farm villager cubicle design is from a famous iron farm by ilmango, so i can almost assure its not from the cubicle itself, no idea how to recreate.

Attachments:

Notice how the villagers on the left are sleeping, as i replaced their beds, but the all others aren't.