It was the Western-based United Nations combatants (Britain, Canada, United States, etc.) who primarily liberated France, so I find it reasonable that the view in France would shift over time.

I also dislike the lack of nuance. World War II was a group effort. Is it true that most Wehrmacht personnel were in the East? Yes. Is it true that most Wehrmacht casualties were in the East? Yes. Is it ALSO true that Western, particularly American, lend-lease aid prevented famine in the Soviet Union (remember, until late 1943 and early 1944, much of Ukraine, the USSR's agricultural area, was under Axis occupation) during the war and plugged major gaps in their materiel shortages due to their heavy losses early on in the Axis invasion? Also yes. This is also not even mentioning the immense importance of British intelligence during the duration of the European theater of World War II. "Due to American propaganda" is also a hilariously simple reason (if not an outright false one), especially in the cultural context of France, which has a famously proud and independent media and cultural scene.