As an interesting note, Germans and Soviets tended to actually have very little problem killing each other due to how personal the war was. Eastern Front soldiers who queston the morality of their actions are a purely Western construct.
That is too much of a generalization. Of course there was hateful propaganda on both sides, and obviously it was very personal for the Soviets who had their country invaded and for both due to the general cruelty on the Eastern Front, but I've talked to German WW2 veterans who very much were torn up about these events many decades after the fact. Maybe losing the war and spending up to 5 years as a POW in Russia gives you another perspective, but considering how absurdly cruel the war in the East was compared to the Western front, I imagine that there are Soviet soldiers too who question their actions, no matter what propaganda made out of it after the war.
After the capitulation and subsequent denazification, it's not surprising that many Germans would question their actions, but during the war itself Wehrmacht hammered into its soldiers the belief that they were fighting subhuman, filthy animals, not people. Despite the West later promoting the idea that German soldiers were all honorable warriors who had no hand in all the atrocities perpetuated by the SS in order to discredit Soviet Union during the Cold War, the standard
modus operandi of Germans in the Great Patriotic War was to rape, pillage and murder their way through civilians with remarkably little hesitation. A lot of the old people I work with still remember those events and you can read about them in enough memoirs to eliminate all possibility of them being just propaganda.
My friend's grandmother is a former partisan, actually, and, as she can testify, when Germans entered her village the people greeted them like heroes and liberators from Stalin, but what followed next is that the soldiers unceremoniously herded all the adults currently present into a barn and lit in on fire. The kids and teenagers, such as herself, were instead sent to another village for "germanisation", which meant, mostly, "slave labor".