u/Big-Perception-6079

I have Denmark as a vassal after recovering it in a war to the Netherlands, now, it had almost 6 million inhabitants, and a few turns later it is only 500k, it lost almost 5k of inhabitants, I already checked and it is not at war, it does not have any epidemic and as far as I know, it is assimilated 100%, does anyone know how to increase the population??