The obvious answer is that Hitler was colonizing other Europeans instead of colonizing non-Europeans which means that the other European empires will expose and condemn any war crimes under Hitler’s regime even as they attempted to hide the fact that the Holocaust was inspired by the fake residential schools that enslave all Native American children in America and Canada or the fact that Nazi Germany commited less war crimes as other European empires. When the British and French learned that they can no longer please Hitler, they decided to free ride in Stalin and make the Soviet Union do all the work despite the greater need for post-war recovery from the Russian civil war that is more destructive than WW1 and the relative underdevelopment compared to Western European empires. Stalin failed to persuade the British and French in a diplomatic meeting, but Stalin eventually force the Western European empires to end their free riding over Soviet Union with a temporary non-aggression treaty with Hitler so the Western European empires will not blandly praise Hitler for genociding Communists and stealing support from working class.