Is it Christmas until Epiphany?: A Liturgical Clarification

I keep seeing the above image on social media. As far as I know, given my admittedly limited knowledge of Western liturgical practice, this formulation, and the related notion of the 12 Days of Christmas, is entirely congruent with the celebration of Christmas in the Western tradition. However, many of the people I’ve seen sharing this are Byzantine-rite Eastern Orthodox Christians—and the formulation doesn’t really work in this liturgical context.