Flamin' Hot was based on a guy's claim that he invented Flamin' Hot Cheetos only for it to later come out that all of his claims were lies. Eva Longoria (the director) said "We weren't making a movie about the history of the Flamin' Hot Cheeto. We're telling the story of Richard Montañez" but the one and only reason anyone gave a shit about his story is because they thought he actually created the Flamin' Hot Cheeto lol. Biographical movies are always fictionalized to some degree but the audience goes in assuming that the premise is at least true. That would be like if you made a movie about Beethoven and then it later came out that he never wrote a single piece of music.

I also found out recently that Julie Powell (played by Amy Adams in Julie & Julia)'s marriage was nothing like we saw on screen. She apparently wrote another book detailing how she cheated on her husband numerous times and then stalked the people she had affairs with. I give this one a pass though and think that making Adams' character completely different from the real person was the correct decision. Portraying her accurately would have legitimately ruined the movie.