Have multiple villagers in one location - will play for several Minecraft Days and when return the amount of villagers have decreased significantly.

Have a open trading hall with 18 villagers / 18 beds.  The only entrances to the hall are fence gates.  Area surrounding is well lit - no mobs can spawn within 50m.  Return several days later and the villager number has been reduced to 10.  This realm was brand new created in 1.18.x.  Farmers are typically the ones to go first - Have lost some librarians.

Other members of the realm have reported villagers disappearing.