Personally, I don't like ugly fighting, but I do like (LOVE) Truth!
The indisputable truth of what we are instructed to do about heretical popes (bolded), is found in the beginning of cuм ex....
"1.In assessing Our duty and the situation now prevailing, We have been weighed upon by the thought
that a matter of this kind [i.e. error in respect of the Faith] is so grave and so dangerous that the Roman
Pontiff,who is the representative upon earth of God and our God and Lord Jesus Christ, who holds the
fullness of power over peoples and kingdoms,
who may judge all and be judged by none in this world,may nonetheless be contradicted if he be found to have deviated from the Faith."Nowhere does cuм ex grant anyone the obligation, responsibility or right to decide the status of popes, in fact to do so is to go exactly contrary to what he says (underlined) above in #1.
That is truth.