12/16 villagers disappeared after the latest update

I had a zombie spawner to village operation. From it I had 16 villagers. After the update only 4 remained. It was in an enclosed room with two golems guarding them. In my entire gameplay, there has NEVER been a mob in there. The place is well lit.

After the latest update, I noticed 12 were gone. Can they be restored please?

It's in the realm, "Sad Mining Hours Who Up".

I spent ages mining gold or killing Drowned to turn them and you've single-handedly made me want to quit this game forever; because if you are going to reverse all the good effort I put in this game, why would I want to play it anymore .