So they weren’t part of the ‘host countries’, at least not of Poland.
I am not excusing them for what they did do - but lets get it right. Silesia and East Prussia were not Polish territory, and certainly not Russian territory.
Russia still has an exclave today. Why has that not been returned to Germany or permitted to govern itself like the other Baltic States?
Much of those "German" lands were stolen from Poland in 1795.