Before the 1.16 update, if hostile mobs (like zombies or skeletons) were in confined area, they would not despawn until killed. After the 1.16 update, if I trap a mob and then leave the chunk, they automatically despawn. For example, I wanted to turn a zombie villager into a normal villager. I trap the zombie villager, run about 30 - 40 blocks to my house to grab a golden apple, and then come back, the zombie villager despawns. This happens to all mobs including passive mobs if they are not in a confined area. But why does hostile mobs now despawn if I go about 20 blocks from them even when they are in a confined area?