In The Wages of Destruction, the first economic history of Nazi Germany in a long time, I stopped reading (at least for a long while) when it got to the part where the Nazi economic plan for the Soviet Union was to starve the residents of the cities and use that food to supply their food constrained Greater Western European Co-prosperity Sphere.

(I.e. the French could in theory make airplanes for the Luftwaffe if they had aluminum. They could use their ore and smelters to do that if they had enough electricity. They would have enough electricity if they had enough coal, but they couldn't feed coal miners enough to keep the sufficiently productive (losing coal imports from the U.K. really hurt them).)

Anyway, to the extent they were able to carry out their planned starvation (haven't read that far yet), you'd expect things to be more grim in the less prosperous cities and it could have gotten into a zero sum game, a Jew betrayed to the Nazis was one less mouth competing for very scarce food.

I wonder to what extent the mortality is a proxy for length and early onset of the occupation.

As for tendency to vote Communist, in areas once occupied people might tend to remember the Red Army fondly.