The saying of this powerful prayer was officially suppressed in 1964, after Vatican II. In our area (the Archdiocese of New York), in no parish that I have attended Mass has it been used, that is, until recently. I have heard members of the congrgatiion say the prayer on their own, but not led by the priest.
Last Christmas,however, I attended a beautiful Novus Ordo Mass at St. Veronica’s in Chantilly, Virginia - the Mass itself was partially in Latin, and the priest said the Mass ad orientem (”facing East”, with his back to the people). After that Mass, the priest led the people in the traditional prayers after Mass as done in the Tridentine rite.
I no longer regularly attend the novus ordo Mass, that is unless I cannot find a Traditional Latin Mass; after every Low Mass, as prescribed in the 1962 Missal, the Prayer to Saint Michael is said by the priest and congregation with the rest of the traditional after-Mass prayers: 3 Hail Marys, Hail Holy Queen, O God our refuge and ou strength, Prayer to Saint Michael.
Nice summary and it sounds as though you were blessed with something tolerable for that Christmas Mass. The other day a nurse asked me: "Do you have a religious preference?" I said "Yes, Pre-Vatican II Catholic". Don't think she knew what it meant but did write it down. Can you imagine a hospital chaplain calling around to parishes asking for a Pre-Vatican II priest? They (traitorous elements of the Church) even managed to screw up Extreme Unction. Who but the devil would suppress St. Michael's prayer and interfere with end-of-life prayers? So, back to the original comment, I have never made it far enough through a Novus Ordo to find out if St. Michael's prayer was said afterward. It is rare that I get to a Christmas Mass as Christmas rarely falls on a particular Sunday when our visiting Tridentine priest is in town.