You know, I've been dwelling on that as of late, due to the regular comparing of Russia's armies with those of Nazi Germany in this forum. Obviously, Nazi Germany's war crimes in the USSR were more extensive by countless orders of magnitude. What does stand out, though, is the proclivity of individual Russian troopers to commit war crimes, which isn't something that could be said even for the Wehrmacht.
The Nazis used human scum like Dirlewanger precisely because many regular soldiers refused to partake in the killings or broke down psychologically in case they did comply. These observations eventually brought about the death camp system (where no one has to pull a trigger and be physically present for the deed). Himmler acknowledged this in his infamous Posen speeches, basically stating that most people outside the SS were too soft to carry out mass murder and would not understand it, necessitating secrecy even in Germany.
In all modern conflicts where war crimes were tolerated or encouraged by the leadership, that task was usually delegated to special units hand-picked for their cruelty or ideological fanatism. This happened as recently as in the Bosnian War, where the majority of the killings was done by Bosnian-Serb special police battalions. A widespread individual proclivity to commit outrages is more a hallmark of pre-modern conflicts.
What I've read on the situation in Ukraine reminds me not of Second World War accounts as much as it does of tales from the Thirty Years' War, which was marked by a general breakdown of social norms and the combatants turning against each and everyone (including their own side and their own civilians). The Russian disregard for basic humanitarian principles isn't just shocking, it's also odd in every sense of the word.