They were expelled of course....look I am not necessarily saying it was fair....but War is Hell, especially when you start one and lose.
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?