Explanation
The losses of Germany on the eastern front are widely believed to be the most significant factor in defeating Nazi Germany and the USSR won the battle of Berlin, the final battle before the German capitulation. Thus Europe widely believed (for a good reason) that the USSR was the main contributor in defeating Germany. With the cold war the perception of the USSR became a lot worse in western countries like France and with increasing anti-USSR sentiment the view flipped to viewing the USA as the deciding factor. The USSR (and the Russian Federation today, even if its government is very anti USSR) viewed itself as the most important force in defeating Germany, especially because the USSR had the biggest amount of deaths. It is worth noting that the USSR was at least commercially allied with Nazi Germany until June 22, 1941 and there was an agreement between the nations on which parts of Europe each could invade and which where reserved for the other.
I didn't disregard your source, I simply pointed out how you utterly lack the basic context necessary to understand its actual impact in cold war french politics. The CIA certainly would have liked to obliterate french leftism but its ability to do so was negligible. I believe you are relying on a frame of reference that is not relevant, and you arent't acquainted enough with this particular subject to realize so. I suggest you be more careful in the future when commenting the politics of foreign countries, lest you overgeneralize and rely on your own preconceptions.
The french communist party (PCF) supported the invasion of Finland and the Baltics while condemning that of Czechia and colonialism. It then supported the Molotov-Ribbentrop pact and the annexation of Poland, which caused a third of its PMs to leave the party. It then supported Nazi Germany against French and English aggression. It then negociated with German occupation forces to continue its activities and ridiculed resistance fighters. Once Germany invaded the USSR, it finally supported the resistance and the allies. It also lied that its leader, Thorez, had been a resistance fighter when he in fact had fled to Moscow. Postwar, it denied the existence of labor camps and the Katyn massacre, and supported Soviet repression of Eastern European uprisings.
This is what I mean by flip-flops. Every single of these, even when obviously contradictory, was justified by the will of the workers and the fight against capitalism; this decredibilized the idea there was a single unifying theory for its action. By the 60s, it appeared that for decades the french communist party was puppeted from the Moscow, had knowingly lied or disregarded its principles in multiple occasions, and defense of the international (or even just national) proletariat was in fact not its guiding principle but rather the material interests of the USSR. This was the main, fatal blow to the party. It had lost all credibility as an actual alternative system and henceforth only subsisted as a political force within the existing system. In this it was somewhat successful since it had theorized a split between revolutionary theory and socdem practice, something which had further eroded its claim to power as well. It for instance refused to support the tentative student revolution in 1968.
That isn't to say US imperialism wasn't an issue. But much of the electorate saw the PCF as hypocrites who only condemned imperialism and dictatorship when it was the West doing it. Anti-imperialism and decolonialism in cold war France went far beyond the PCF so that wasn't really something they had an edge on.
Even after destalinization the USSR was a brutal dictatorship that criminalized dissent under the idea that the state is the party is the class. Therefore (1) democracy isn't needed as it is merely needed to place the correct class in power for true democracy and (2) an enemy of the state is a class traitor and must be destroyed. Public protests were put down with overwhelming force such as the 1968 Prague spring. Individual dissidents were given bogus psychiatric diagnoses in order to indefinitely detain them.
Many leftists in France pointed this out and fought for the rights of the people under Soviet rule. For instance french trotskyists fought for the liberation of Leonid Plyushch, Jiri Hayek, or Edmund Balunka.