Ok, I’ll give you one concrete example. After the second wave of battles in the Albigensian Crusade, Catholics in the north of Italy were not terribly supportive of the fighting. From what they knew of the Cathars that lived among them, their sense of morality tended to be exemplary, they were pacifists and good neighbors. They had bad doctrine and were certainly heretics if not entirely non-Christian, but good people who didn’t deserve to die. This, at least, is what Catholics in the north of Italy had to say.
In order to combat the spread of disfavor toward the Crusade, the Catholic clergy in Italy launched a campaign of vilification against these heretics. They knowingly (and quite effectively) bore false witness to the tune of incest, homosexuality, and bestiality among other things that weren’t necessarily all sexual, claiming that the heretics encouraged these things and did them in secret. As a matter of fact, the French word associated with the ethnic origin of these heretics came to be closely associated with homosexual acts, and that word, once associated thusly, made its way into the English lexicon strictly as a pejorative term having nothing whatever to do with ethnicity by that point- and that is why “bugger” means what it means. Did you ever wonder about that? I did. It’s derived from a French term for Bulgar, but it retains none of its ethnic implications.
At any rate. That particular crusade was questionable in and of itself, but when the Catholic clergy engaged in a coordinated effort to spread misinformation via propaganda in the interest of helping the laity be more hawkish, that would be a time when the Catholic Church removed its white hat. By the way, some of your modern or near-modern Catholic historians will present those details about the Albigensians as if they are basic historical fact, but they are actually lies and it’s a textbook example of bearing false witness on a large scale.
That doesn’t involve the promulgation of any particular teaching that is binding on the conscience of all Catholics, it’s just some lies about heretics designed to help people hate them more. But I would say it is an example of the Catholic Church removing its white hat.
In my defense, you did ask for it. Repeatedly. Does that satisfy you?