That is true, Polish citizens are not citizens of Germany. Their civil rights are not the same. You seem to imply that they should lose their human rights (which are different than civil rights), which they should not.

But the occupied Polish don’t have a right to vote in German elections, or access German healthcare, etc. it doesn’t mean that they shouldn’t, it means they don’t have a right to it. You must understand that there is a difference between what one should be able to do and what one has a right to.

I believe you are capable of understanding this.