When I'm playing the game and turn off my switch, when I turn it back on, occasionally random things will despawn. Most frequently it's my minecart with a hopper in it. I have 3 of them running on an automated farm, and multiple times when I turn the game back on, they are gone. I was also riding a very good horse with diamond armor and when I turned the game on it was gone and I was just standing there alone, and today, one my max level villagers with a name tag despawned.