For all our dodgey, lustful, murderous, lying, scum bag fellows that have dotted the Papacy during the last 2000 years, no Pope has ever altered or attempted to alter the Truth of the Church or the doctrine She teaches. Christ promised the gates of hell would not prevail against the Church, no evil can be taught by it. A Pope might say something stupid, do something evil, but never has a Pope done so under the office of Papal infallibility.
Pope Honorius was condemned as a heretic by an ecumenical council with the approval of his successor. Denying that is true is nothing but historical revisionism.
Papal infallibility ex cathedra isn't in question here.
And again we must not think that in everything and everywhere his judgment is infallible, but then only when he gives judgment on a matter of faith in questions necessary to the whole Church; for in particular cases which depend on human fact he can err, there is no doubt, though it is not for us to control him in these cases save with all reverence, submission, and discretion. Theologians have said, in a word, that he can err in questions of fact, not in questions of right; that he can err extra cathedram, outside the chair of Peter, that is, as a private individual, by writings and bad example.
-- St. Francis De Sales The Catholic Controversy
The ultramontane idea that the Pope is some sort of God on Earth whose personal actions are unquestionable is what is in question.