Context: The German soldiers were fed propaganda that Slavs were inferior and barbaric. This caused many to kill prisoners burn down villages, mass rape, etc, cause they believed in that ideology of genocide as part of
Generalplan Ost. The German soldiers are scared because they expected their enemies to do to them what they did to them. Now some soviet soldiers did take revenge and do the same thing back but it wasn't an official state policy like GPO and the other criminal orders were.
https://en.m.wikipedia.org/wiki/War_crimes_of_the_Wehrmacht
for further reading since its harder to explain shit in mango dex forum
also the clean wehrmacht myth is a giant lie