If I go into creative on a server that I'm an op on and then am disconnected for some reason (be it connection related or me choosing to leave the game) and then I log back in, I am in survival. If I happened to be flying at the time that I was disconnected, then I end up seeing "<username> fell from a high place" if I was high enough to take enough fall damage to kill me. Obviously this is preventable if I am manually disconnecting but if I am disconnected for any other reason there's really not enough time to type /gamemode 1 before I hit the ground