Many have noticed that mobs in Bedrock edition don't ever seem to despawn, even when being out of range of any players and thus should be in unloaded chunks. I noticed this with Zombie Villagers, which ordinarily would despawn when there are no players in range to keep them loaded. I played alone and travelled far away and even to the Nether and every time I came back I still had a bunch of zombie villagers trapped in a room.

We also noticed that the life in our oceans is completely void, no fish, squid or dolphins. Only the occasional drowned. I suspect the above bug to be the culprit.

Please ensure that mobs are properly removed from the game world when moved into unloaded chunks.