The claim that the current Polish government cannot be held culpable for the actions of the Polish occupation government or government-in-exile during WWII holds some degree of truth.

Unfortunatley, the degree and type of complicity and cooperation with the invading Germans on the part of ordinary Poles, at least in some places, is quite relativley-documented.

Most famously, the scholar Jan T. Gross wrote a book Neighbors: The Destruction of the Jewish Community in Jedwabne, Poland. This book documents the willing complicity of Catholic Poles and rounding up and deporting their Jewish Polish neighbors and seizing their assets. Similar incidents are documented at other towns and villages across Poland and Ukraine. This is not a set of episodes the the current Polish state or Polish people wish to dwell upon, understandibly, as they feel is detracts from their own suffering under the Nazis later in the war.

Our very own /u/estherke can doubtlessly explain this topic in greater detail than I can.

But bluntly, there is subsantial evidence that at least in the initial stages of the German occupation, quite a few Polish people were downright enthusiastic about the opportunity to help deport their neighbors and seize their properties. This fact is inconvenient for the current narrative of Polish national identity, which emphasizes their collective suffering under both the Germans and Soviets.