On hard difficulty, we have had multiple instances of mobs, many of which nametagged, despawn. We made a village out of cured Zombie Villagers and made an iron golem for the,. The village was underwater and of course has no water inside and is capable of supporting life (were not THAT stupid). And the game registered it as a village as cats, wandering traders, and now iron golems are spawning in the village. But some of our villagers even though there are more than enough eligible beds in the village and it has all the amenities of an above ground village, some our nametagged villagers despawned. Even our iron golem which was also nametagged despawned. We were out of render distance for about 3 to 4 in game days and when we returned, there were missing entities.