Interesting. Look's like the "old.reddit" plugin breaks that link. Weird that they have to source a reddit thread rather than the actual study. Red flag for sure that they're full of shit. https://www.ifop.com/publication/la-nation-qui-a-le-plus-contribue-a-la-defaite-de-lallemagne/ Now is that graph valid... well looking at the "study report"... It's like 3 pages of content that doesn't actually outline much of anything and conflates with itself. The report says it was 1200 people 18 and older... the website says sample size of 995 people. The study report says 1200 people sample for the 2015 figures, except it was actually taken in may 2014. And no figures about how many people in the previous years. So I would worry about how "valid" this is to begin with. But let's look at the content on the original page.

The study even cites the reason this "perception" could have been a thing... (translated, possibly poorly. Check yourself! But my high school french skills only go so far).

Virginie Sansico, a historian specializing in World War II, sees these results as a certain logic: “Under De Gaulle, who was anti-Atlanticist, one was not quick to maintain the memory of the Landing. Moreover, the Communist Party has long helped to value the Soviets, when it had a strong influence. The first State-backed landing commemorations took place only in 1984, organized by Mitterrand: they mark a break in public opinion.”
“In Western Europe, the Allied Landing was crucial, but in the eastern countries, Stalin’s army still played a great deal behind.”

So actually it looks like Russia propaganda in the 1940s thanks to De Gualle's personal opinions on the matter.

So I'm going to go with, not only does that graph itself mean nothing in this conversation, but the story behind it actually damns the argument they're trying to make, especially since the matter is well known https://www.tandfonline.com/doi/full/10.1080/01402390.2016.1220367.