Apparently, if you have the ‘The Lady of the Lake’s Vigil’ boon (when you are above 75% health, you take half the damage inflicted on nearby allies instead of them) and the ‘Unquenchable Thirst’ Slaanesh curse (players suffer damage over time, drinking potions restores health lost) active on the level, this will cause the player character to constantly complain of friendly fire from their various teammates. It is both hilarious and annoying.
This is something I’ve noticed when Chaos Wastes was released back in April. I thought it has been fixed but was surprised that the bug still happens as of the Grudge Marks update.
An Apr. 2021 bug report of this issue: