I remember in World of Warcraft, your internet connection could drop completely and you wouldn't notice until you realized you hadn't seen mobs or another player for a while.

World of Warcraft is not fully server authoritative. There have been speedhacks going on. Also, an entire guild was banned once because they modified the client-side model files to remove the stairs in the dungeon, allowing them to fall down the pit and skip most of the dungeon.

I found this out recently when playing wow classic I somehow fell out of the sky, and survived when on a computer "controlled" Griffin, if I had any control of the bug I could use it to drop off in more convenient locations

I had that too, if taking the flight path from Goldshire to Stormwind and my game crashed/disconnected, I often found my character next to Stormwind gates.