“Arguably, the Soviets did do most of the heavy lifting on the land campaigns against the Third Reich.”
It isn’t even arguable; they did. How that translates into keeping territories of other countries that had been victimized by the Nazis is beyond me; by what right would they keep Poland?
Our collusion with the USSR guaranteed that we would fight wars in Korea and Vietnam because we rescued Stalin while selling out Europe.
Poland had not existed since the 18th century. After WWI it was reconstituted out land taken from Germany and Russia. As far as the Russians were concerned, they were getting some of their own back. I’m not saying it was right, just that they saw it that way (sorta like the Chinese believing that every land that ever paid them tribute is actually a stray part of “Greater China” or something like that...).
If we wanted to fight Germany, we had to collude with the Soviets. There was an example of the Russians signing a separate peace with Germany in WWI. If the Russians had signed a separate peace in WWII, the Germans would have been able to double the forces facing us. If didn’t want to fight Germany, well, we were not offered that choice.