Russia is at war with Ukraine, capture soldiers are rightly and traditionally placed in POW camps. There is no war crime in that, even though the concept of a war crime is silly. War itself is a crime between one side or another. What should have happened to the Germans who starved or gassed people in camps, should have been Germans trying them and punishing them. Big bad Allies had to do the deed themselves, when it would have been better for all sides if the guilty would have been judged by the enablers and the blameless. If Americans commit crimes in a war, do we not punish the people ourselves?
This has nothing to do with POWs.