I am wondering where SimpleMan got the idea that the Solemnity of the Immaculate Conception is this year being transferred to the preceding 2
nd Sunday of Advent? He gives no source or citation. That aside, while I can’t cite ecclesiastical directive, typically if and when a commemoration on the Roman Calendar is transferred it is transferred ahead, not back.
I consulted my parish calendar (Diocese of Spokane, WA), the iPieta app, the Catholic Calendar app (Universalis.com), the calendar of lectionary readings from my Verbum scripture study software and app (verbum.com). EVERY SINGLE SOURCE, yes EVERY ONE, shows the Immaculate Conception being observed on Wednesday December 8 with the rank of a Solemnity.
It is true that in the United States when a Holy Day of Obligation occurs on a Saturday or Monday the obligation is typically dispensed, but parishes are encouraged to provide for additional Masses at times when working people can attend, typically in the evening.
Here is an article
https://www.learnreligions.com/when-is-the-feast-of-the-immaculate-conception-541628on the dates for observance of the Immaculate Conception. Again, one notes that if the feast is transferred it is transferred AHEAD, not back. However typically in Washington State when the Immaculate Conception falls on a Sunday it takes the place of that Sunday.