Canonizations are most certainly covered by the secondary powers of papal infallibility, as they pertain to the matter of Faith. Especially given that these individuals are being raised up as worthy to be offered at the altars of the Universal Church, having a heresiarch or apostate canonized would be a great danger and scandal to the Faith.
Which is the issue surrounding the canonizations of Bergoglio and the Vatican II "popes", as he uses very direct, declaratory language in their canonization pronouncements. Therefore, the rejection of these individuals, such as JPII, John XXIII, Paul VI, et al, would actually constitute grave disobedience to the Pope. Meaning, those R&R outlets, such as the SSPX/SSPX-R, Indult groups, etc., that implicitly or explicitly reject these canonizations while professing these men as true popes are in a bit of a rock and a hard place canonically-speaking.