Greetings everyone, I'm asking for your help to determine if what I've witnessed is a bug or something else. I'm not really sure what could have happened.
As Italy I've started colonizing Africa. After getting a foothold in the region of Congo, I've declared war and annexed Kongo, taking control of their province. A few months later I noticed that a decentralized country, Yaka, took control of that province of mine, but I received no notification as far as I'm aware.
A picture might help (on the left after annexing Kongo, on the right a few months later):
View attachment 922471
I'm pretty sure Yaka didn't start any diplomatic play or native surprising against me, but I would never have backed down anyway.
Can anyone explain to me what happened?