I believe it's much more simple than you all think.
Benedict XV taught heresy on several occasions, therefore he was an antipope. Pius XI followed him and recognized him as a valid pope, and he had many ambiguous teachings savoring of heresy himself. He was an antipope, and so it goes on down the line to the present day, with the heresy and apostasy getting worse and worse, culminating with John Paul II and Benedict XVI, who both boldly and shamelessly fornicate(d) with the enemies of God.
Anyone who recognized Benedict XV or anyone of his anti-successors as true popes is at least a schismatic, including Siri, Pio, Lucia, Malachi Martin, Ludwig Ott, etc. who are all red herrings, which satan wants us to obsess over.
Someone might attack me for this:
Catholic Martyr, if what you're saying is true, then almost everyone in the world is going to hell and has been for close to 100 years!
To which I would reply:
For there shall be then great tribulation, such as hath not been from the beginning of the world until now, neither shall be. And unless those days had been shortened, no flesh should be saved: but for the sake of the elect those days shall be shortened. Then if any man shall say to you: Lo here is Christ, or there, do not believe him. For there shall arise false Christs and false prophets, and shall shew great signs and wonders, insomuch as to deceive (if possible) even the elect. Behold I have told it to you, beforehand.
Anyone who accepts that a person who claims to be pope while inculcating heresies is actually an antipope, will see that my words are true.