Taking your question seriously, for the American propaganda look at what the news did to Trump, from Russia Collusion to January 6 and everything in between.
For now, this is how I think it works here. U.S. propaganda is controlled at the corporate and upper political levels using a "official narrative" (agreed lie) and runs with it for as long as they can. When running the narrative, we, the ordinary people, are not allowed to question or hold accountable those in power who create the narrative (remember November 4, 2020?).
Search on "who owns the news" or "media consolidation". From Media Consolidation: The Illusion of Choice , in 1983 50 companies owned 90% of the American news, in 2011 90% was owned by 6 companies. Before 2010, there was much more room in the mainstream news for disagreement, so one view could not dominate the press without getting challenged by other members of the press who had equal means to challenge a narrative.
When they can't they drop it stage by stage. The news is now admitting that Russia Collusion was a fraud, while still holding onto January 6 was Trump's coup. In a few years when they have something else to attack, then maybe they will walk back on January 6.