Stalin was given parts of EU yes. Soviets did after all do quite a bit to win the war. Their losses were the most of any country I think they deserved Ukraine and parts of the EU. What they did with it after was horrible. Stalin was worse than Hitler in that case.
If The Soviets didn't get anything they would have been butthurt and started more conflicts to take what they thought they deserved. Making a deal with them at the time was the best possible choice for peace.
What a pile of steaming crap. They also did quite a bit to start the war. Didn't they invade Poland along with the Germans? When they were the invaders it was all good, but when their allies, the Nazis, turned against them they suddenly became the martyrs and the saviors of Europe
They deserved Ukraine? I don't know where you are from, but If your country was now attacked by one neighbor and liberated with the help of another you wouldn't just give them everything and become a part of their country to show appreciation.
And it's important to say Europe wasn't liberated by the Russians, but with their help. Do you think people of every occupied country just stood and watched?