You should read again, I'm not justifying anything and i said "hopefully they don't", but if you don't see why a person seeing the carnage uttered by the invading barbarous Russian army might want to enact revenge including through illegal means like shooting POWs ( the guys who just went around looting, raping and murdering civilians) I don't know what to tell you.

For a precedent, the Soviet army treated German POWs and worse, civilians, atrociously. But they had just suffered through a bitter war of destruction where they themselves were treated similarly.

It's up to the commanders to keep things clean and not let the anger spillover. Of course the Soviets didn't care, and on the contrary encouraged atrocities. So far the Ukrainians seem to be taking the high road, and all the better for everyone.