Outriders griefers are kicking co-op players out of endgame missions before they can get their loot.
The game's endgame, dubbed Expeditions, features a number of rock hard encounters that, if completed, reward powerful loot.
These Expeditions only reward loot upon completion. After clearing the final encounter, you trot over to a drop pod, activate it, and it spits out your loot. This is where the trolls are stepping in to ruin their victim's day, kicking them out before they can reach the drop pod.