You are speaking of the formula of episcopal consecration that was promulgated by Pope Paul VI in 1968. According to extremists, this marked the decline of the episcopacy, and hence, after this point, priests began to die out as no valid bishops were being created.
They make some argument about how the new episcopal consecration does not reflect the office of Bishop to Teach, To Govern, and to Sanctify. Since the main prayer only uses the phrase “Governing spirit” and doesn’t refer to the full ministry of the Bishop, it is invalid according to extremists because of the three requirements for a validly confected sacrament: Form, matter, and intent. In this case they say that the Form is compromised in that it no longer reflects the role of a bishop (the consecratory prayer that is).
THeir justification for this point of view lies in Pope Leo XIII’s condemnation of anglican orders as invalid because they failed to reflect the Catholic priesthood. Well, these new consecration prayers of the bishop fail to reflect the Catholic teaching on the episcopacy, therefore those Bishops consecrated after 1968 are invalid bishops. If you do the Math, that means the last valid priest was consecrated in 1967. And the youngest a priest can be is 25. So, 2011-1967=44+25=69.
Which means basically, the youngest validly ordained priest in the world (If you don’t count schismatic ordinations) is 70.and the oldest is probably 95. A bishop has to be 35, so the youngest “Valid” Bishop wherever he is in the world is 80.
Yeah, I know.

THat’s the so-called argument anyway.