That may need to be updated. I'm looking at a Latin breviary from 1971 and +John Damascene is Dec. 4 and I believe it remains so. No idea when we moved it.
.Of course, today is Sunday, so the memorial gives way to the celebration of the Second Sunday in Advent.
Sorry. I keep relying on Dad's 1956 +Joseph's Daily Missal! Does the priest mention whose feast day it is on Sundays? Ours do, at the very end of the Liturgy they are commemorated.