I've been running a game as a server with the LAN game option and letting it run. I've had pretty few issues until the 1.16.221 hotfix. The game can't seem to stay running for more than a few hours. It'll lock up and freeze or crash to desktop. When I log back in some or lots of our name tagged villagers, entities and other mobs despawn. This completely ruined our villager trading hall as we name them by what trade they sell. Half of our villagers despawned in one crash alone and needed to roll back a save from a previous week. DAYS of work lost and a lot of angry players.

Steps to reproduce:

Open a world.

spawn in a bunch of mobs... villagers, zombies, etc.

Name them and/or trap them to keep them from moving/enclose them in a room (to simulate a trading hall)

Either let the game run for a few hours until it crashes or force crash the game with ALT F4 or something. Every now and then some of the mobs will no longer be there.