In the first Christian Millennium, It often happened that a liturgical book offered a proper preface for every single Mass formula. As well as the obvious references, I also offer you, in illustaration, our own Anglo-Roman Leofric Missal.
During the second Christian Millennium, the number of prfaces was drastically reduced.
After Vatican II, there was a new resurgence of prefaces (I don't know what the Conciliar Mandate was for this).
In 1759, Pope Clement XIII had extended the Trinity Preface to all Sundays not in the seasons of Christmas-Epiphany, Lent; and Easter-up-to-Trinity-Sunday-inclusively. Previously, the Common Preface would, fairly generally, have been used.
2015A had proposed to extend the 1738 Advent Preface to the entire world. It also floated the idea of a Preface for the Gesima Season; a Preface which I discussed at some length this year on February 8 and 9. I am not going to repeat that discussion here.
2020 does not repeat these suggestions. It thus in effect leaves the Trinity Preface to be used throughout Advent and "Pre-Lent". The "Note for the presentation" explains why.
The Congregation decided to provide "texts for particular occasions such as feasts of Saints, votive Masses or ad hoc celebrations, without making any changes to the celebration of the temporal cycle. This choice was made in order to safeguard, through the unity of texts, the unanimity of sentiments and of prayer that are appropriate for the confession of the mysteries of Salvation celebrated in what constitutes the backbone of the liturgical year. In addition, the historical development of the Corpus Praefationum of the Missale Romanum up until the middle of the 20th Century shows a general movement towards the use of new prefaces for occasional celebrations rather than for celebrations of the temporal cycle."
So the Gesima Preface never got lift-off; the Advent Preface of 1738, indicated in the SSPX French-language ORDO, goes AWOL.
But not necessarily for ever. "In addition, it should be noted that the Decree does not cancel any eventual concessions of proper Prefaces granted in the past, and therefore in those particular cases where there already exists, on the basis of preceding permissions, and for the same liturgical circumatance, a particular Preface, one may choose between that Preface and the newly approved text.".
It is not clear to me what this means. Is it looking to 'eventual' regrants of a preface such as the 1738 Advent Preface; or ("already exists") affirming the abiding validity of old grants?
In my unhumble opinion, the sensible and real choices are either to argue
(1) that the CDF should be asked to reconsider the matter of the Advent and Pre-Lent Prefaces; or
(2) that the Roman Rite, with its severely and primitive binitarian instincts, does not favour the imposition of a Trinitarian character on most of the Sundays of the year, so we should go back to the pre-1759 situation and use simply the Common Preface on Sundays through Advent and Pre-Lent; or
(3) that Sunday is by nature Trinitarian; as long ago as the pre-Gregorian exemplar which Moelcaich the scribe of the Stowe Missal copied, the preface has had a Trinitarian character ... rather as it does in the Byzantine Rite. So ... back to Clement XIII.
On Monday, Dv, I shall discuss the Calendar in the new Decrees.