I think it started with the retcon of Obi Wan being a liar. When he told Luke the truth in Star Wars, because at the time Darth Vader was just Tarkin’s henchmen and not Luke’s father.

Then you had the whole point of view speech in Return of the Jedi. And in the novelization the revelation Anakin’s fall was Obi Wan’s fault and hubris.

As for the Jedi having flaws the only flaw Annikin Starkiller had in the rough draft screenplay was that he lacked discipline for his lack of celibacy. Its truly bizarre, he isn’t called out for punching out Leia Aquilae.