I looked up the text of Ratzinger's resignation speech (unfortunately it's an English translation, but) and this seems to be the operative part:
.
Maybe that's why the Bennyvacantists seldom quote that part of the speech, even though it's the most important part.
Ann Barnhardt addresses this:
In April 2005, Joseph Ratzinger took on the awesome, ontological,
personal responsibility of the Papacy: the Episcopacy of Rome and the Vicarship of Christ. Nearly eight years later, however, the pontiff felt that his 85-year-old stamina no longer permitted him to continue the “functional” duties of “words and deeds.” He will step down from them, but he will remain in the spiritual “suffering and prayer.” He says all this quite plainly in his official “Declaratio” of February 11, 2013:
my strengths, owing to an advanced age, are no longer suited to an adequate exercise of the Petrine ministry. I am well aware that this ministry because of its essential spiritual nature, must be carried out not only with words and deeds, but no less with prayer and suffering.
vires meas ingravescente aetate non iam aptas esse ad munus Petrinum aeque administrandum. Bene conscius hoc munus secundum suam essentiam spiritualem non solum agendo et loquendo exsequi debere, sed non minus patiendo et orando. (Emphasis mine)
Benedict admits his physical strengths no longer allow him to adequately wield the Petrine ministry [munus Petrinum], this ministry [munus] is essentially spiritual in nature, but nevertheless, humanly speaking, must be functionally administered in words and deeds, he therefore concludes:
well aware [reason] of the seriousness of this act, with full freedom [free will] I declare that I renounce the ministry of Bishop of Rome, Successor of Saint Peter, entrusted to me by the Cardinals on 19 April 2005, in such a way, that as from February 28, 2013, at 8 p.m., the See of Rome, the See of Saint Peter, will be vacant…
bene conscius ponderis huius actus plena libertate declaro me ministerio Episcopi Romae, Successoris Sancti Petri, mihi per manus Cardinalium die 19 aprilis MMV commisso renuntiare ita ut a die 28 februarii MMXIII, hora 20, sedes Romae, sedes Sancti Petri vacet… (Emphasis mine)
Did you catch the anomaly? You probably did not, if you only read the English.
In the first quote from the Declaratio which we reproduced above, Benedict uses “munus Petrinum” to describe the
essential spiritual nature of the “Petrine ministry;” he is able to fulfill this “munus” through suffering and prayer but is no longer able to do so through words and deeds. In the second and concluding quote from his Declaratio, he declares that he renounces the “ministry of Bishop of Rome,” stating in Latin: “
ministerio Episcopi Romae.”
Why, may we ask, did he suddenly replace “munus” with “ministerio”? Why abandon the consistency of his narration? Likewise, why abruptly change from speaking of the “Petrine” ministry or “munus
Petrinum,” to “ministerio
Episcopi Romae,” “Bishop of Rome” instead?
Actually, Benedict is being consistent.
He told Seewald that “he remains within the responsibility he took on…the office enters into your very being.” Accordingly, in his Declaratio, he never renounces the essentially spiritual munus Petrinum.
Likewise, he told Seewald that due to weakness of age he stepped down from the functional aspects—and so he did renounce the “ministerio” of
Bishop of Rome.
https://www.barnhardt.biz/2021/03/12/dr-mazza-guest-post-its-nothing-business-its-strictly-personal/