So, i break the crossbows of some pillagers(by making them shoot at 6 layers of snow) and something happens when i put them in the containment chamber(i don't know if the chamber matters) and then after some time one pillager holds their right hand like in the screenshots.
it does not affect gameplay in any way, but its deeply disturbing. (reloging fixes it UNTIL you get in their line of sight)
Edit: The AI makes them look at you(which adds to the weirdness).