Weather fighting
First of all, Germans don't lack cotton-padded clothes. When guderian proposed to Hitler that the troops had no cotton-padded clothes, Hitler said that the cotton-padded clothes had already been issued. Because a large number of German logistics transportation lines still use mule and horse transportation, it is difficult to ensure that enough cotton-padded clothes are delivered to the troops. After all, the infrastructure of the Soviet Union is still very backward. Although the German frontline troops have been mechanized, the logistics troops are still mules and horses.
Secondly, the reason for the defeat of Stalingrad Germans is the particularity of street fighting. Germany's technical weapons can't give play to any advantages at all, and the war has returned to the true colors of fighting between soldiers. In this case, the Germans naturally failed.
Finally, there are a large number of Soviet guerrillas in the Soviet Union, and these guerrillas have done large-scale damage to German railways. Moreover, the railways used in the Soviet Union are wide gauge, while those used in Germany are narrow gauge. As a result, a large number of German railways in the Soviet Union had to be renovated and resurfaced.