This article distinguishes ex cathedra teaching from infallible teaching, ie there are infallible teachings that do not fit the definition of ex cathedra teaching from Vatican I.
The way I understand it, is that at Vatican I they defined an extraordinary infallibility, but affirmed that under the guidance of the Holy Spirit, the Church teaches infallibly in other situations. Those other situations are not described.
With
Ad Tuendam Fidem John Paul II changed the profession of faith to include an affirmation of he ex cathedra teaching as described at Vatican I; a second category of teachings related to to the faith by reason or history that must be held wih as definitive an assent as in the first category; and three, other things the Church teaches which demand a religious submission. Cardinal Ratzinger wrote a
commentary on Ad Tuendam Fidem explaining this with examples, which is why I cited Benedict XVI instead of JP2 who really is behind the change.
Before
ATF there were two categories, ex cathedra and other unspecified doctrine. After
ATF there are three categories, ex cathedra, definitive, and other unspecified doctrine. So
ATF added a new category of infallible teaching to canon law. Those doctrines had been unspecified infallible teachings before, and now were defined as specificly infallible doctrines.
I could be wrong in how I understand it. But I think this new category is a sign of what Congar called creeping infallibility, as is the behavior in the OP. I am not saying here is anything wrong with the new category, just that it specifies more of what can be considered infallible.