Is that part of Vatican II.
I just finished reading a book about Mother Angelica and EWTN. In it, she had her nuns read Vatican II in its completeness.
What they discovered is that the language of the Mass was NEVER changed — thus she followed the Pope and the Masses on EWTN were changed to Latin Masses.
This is in response to the New Mass of Paul VI (which was promulgated as part of Vatican II). I’m not talking about latin vs vernacular (which I think is what you are focusing on). I am talking about significant changes from the traditional liturgy to the new not-so-Cahtolic liturgy.