https://spectator.org/pope-francis-defends-restrictions-on-tridentine-mass/
Francis explained that this so-called disease of indietrismo is why he has restricted the celebration of the Tridentine Mass.
“After all the necessary consultations, I decided this because I saw that the good pastoral measures put in place by [Popes] John Paul II and Benedict XVI were being used in an ideological way, to go backward,” he said.
It is sadly true that there are some whose devotion to the Tridentine Mass is an ideological one: they reject the Second Vatican Council, they reject Pope Francis, and some even reject all popes since Pius XII, who died in 1958. Such devotees effectively choose a particular form of the liturgy — admittedly, a breathtakingly beautiful form of the liturgy, one long held in the highest of esteem — over unity with the Catholic Church, making them schismatic.