When Phantoms spawn after an individual player hasn't slept for 3-4 days, they will target and attack any other player within the vicinity, regardless if the other players have slept or not.

In multiplayer situations, this can lead to players being punished with Phantoms even if they had slept the night before or within the 3-day limit. And if each player has their own individual Phantom spawns, this can either lead to an unprecedentedly large swarm attacking everyone, or waves of them throughout the night.