The commentator I was replying to was referring to Washington Post admitting that the "Russia Collusion" scandal that went for over a year was corrected silently by them and they admitted it was basically all fraud, but that MSNBC and CNN have made virtually no corrections to this day on that specific issue.

I was not speaking to that MSNBC or CNN has never made corrections broadly-speaking, but rather that they would not back down on a story that is now broadly considered (according to the Washington Post, no right-wing sympathizer) debunked.