Please read as I do not think this is the same as "Lost all pets, entities and NPCs when log out or leave area":

Playing with my wife over a Lan game. from time to time we notice a missing villager. Right now our village population is 40, but we can only see 35.

Their beds are USED but nobody sleeps on them. Their jobs are USED but nobody works on them, they simply don't exist, but if we remove and replace the bed, the green sparkles of it being used are visible. Same with the job stations.

I am not new to Minecraft and I know they did not run away or got stuck in some cave. Just in case, we searched as far as 200 block from the village center down to -50 and did not find them. They are not in lit areas, and I don't think they are in unlit areas since they would be killed by zombies.

To add insult to injury I made a copy of the world, went to creative and removed all terrain (/fill with air) in increments of 5 block tall all the way to 32 and could not find them.

Since I cannot find them but they count towards the village population, use the beds and the job posts, I cannot even kill them to get these placements back, so we already have a "dead house" we keep adding their respective jobs and an extra bed, we call it the "missing room".

Every day a new villager goes missing, and it is killing the experience. 

I have been playing 1.18 since launch separately in my own local world and I have major villages with 30+ population and this DO NOT happen.