Yes the winter war was fucked but it doesn't excuse https://en.wikipedia.org/wiki/East_Karelian_concentration_camps

East Karelian concentration camps were a set of concentration camps operated by the Finnish government in the areas of the Soviet Union occupied by the Finnish military administration during the Continuation War. These camps were organized by the armed forces supreme commander Carl Gustaf Emil Mannerheim.[1] The camps were intended to hold camp detainees for future exchange with the Finnic population from the rest of Russia. The mortality rate of civilians in the camps was high due to famine and disease: by some estimates, 4279 civilians died in these camps, meaning a rough mortality rate of 17%.[2]