Dr. Taylor Marshall on his YouTube show explained why after Archbishop
Carlo Maria Vigano said that the Francis Abu Dhabi statement is "blatant
heresy" that it is possible "Francis has lost the papacy":
"[Vigano said] this [the Abu Dhabi statement] is a blatant heresy... Let's pause there. This gets into St. Robert Bellarmine where he says a manifest heretic immediately and de facto loses the papacy. So, if Bellarmine is right and Vigano is right that means that Francis has lost the papacy... then Bellarmine would also say there is a general council that then declares the deposition that the pope has fallen for manifest heresy."
(Dr. Taylor Marshall YouTube Show, "Archbishop Vigano calls on Pope and Bishops to Repent Amidst Corona Crisis," April 1, 2020, 16:16-16:58)
However, theologian Cardinal Raymond Burke disagreed with the YouTube podcaster Marshall's claim that a "general council" is needed when the Catholic World Report (CWR) asked him:
"CWR: Who is competent to declare him to be in heresy?"
"Cardinal Burke: It would have to be members of the College of Cardinals."
(Catholic World Report, "Cardinal Burke : 'No, I am not saying that Pope Francis is in Heresy." December 19, 2016)
Note that Burke said "members of the College of Cardinals," not the whole College of Cardinals many of whom may
be presumed to be heretics. That sounds like a imperfect council not a "general council."