Villagers and other mobs despawning

All of my passive and agressive mobs (cows, charged creepers and rare other mobs) suddenly despawned. I was playing the game in the End, farming ender man and when I came back to the overworld all of my cows, sheep, villagers, charged creaper, phantom and other mobs deapawned. All of the rare mobs were nametaged but still desponed. All of the grinding rare mobs is wasted. This occured on october 20th 2021.