If I understand the system correctly, if I transport one point of a 15-point factory back to the rear, after it recovers the damage level it suffered because of moving, it will start to grow in size back to its original value.
Does the same thing apply to manpower levels in Soviet cities? So some time ago, I recaptured Tambov. It had a population of 16 at game start. When I recaptured it, its population was 4 and was damaged for like 40 percent. Now the 40 percent has gotten down to zero. Are the missing people going to begin to come back? If so, do they come back from the places to the east where they took refuge, or is there a Soviet baby boom filling the place up?
Historically, there was obviously a lot of mortality in urban populations under German control. The Germans wanted it that way and cut rations well beyond the survival level, as well as conducting mass murder of targeted populations like Jews. However, rural outmigration did refill Soviet cities pretty rapidly; one reason why there are all those terrible apartment blocs in Russian cities today is because of the enormous rush to house all those folks after the war.