Germany paid Poland $8b in reparations in 1992: https://en.wikipedia.org/wiki/World_War_II_reparations

That wasn't reparations, that was retribution for slave labor for those forced to work in German factories. It's a start, but also about two orders of magnitude less than what Germany should pay, given the atrocities they committed in Poland. About 2-3 millions of civilians were killed during the whole war (and I mean ethnic Poles, not the Jews living in Poland, which are additional 3 millions victims)

A sibling comment highlights the problem I'm driving at — how can we agree that the amount paid is sufficient? Who can definitively say that?

This is true for historical systematic oppression of any kind.