Someone else's religions freedom peasant faction cause MY land to become appart of the peasants realm

[Brodo swoggens]

I'm playing Alt Clut to form Cumberland and i get so close to doing it only for all of my land to switch with the peasants land when the neighbouring vikings loose their peasants war.

I didnt take part in that war but i did invade the vikings earlier for a province in the same duchy, the thing is i didnt just loose that one county, i lost MY ENTIRE DUCHY AS WELL AS ALL MY PROVINCES OUTSIDE IT EXCEPT MY CAPITAL. IDK how tf this happened, they literally took the duchy title off me even though i was never at war with the peasants and now i'm just a one county earl with no prestige because for some reason they took that too.