Her headdress still more or less look like a Qitou (旗头) to me, but seemingly the artist used a little bit too much force on the creative side (or, altered a bit too much), so it starts to look also like a Fengguan (凤冠) in someway
It's perhaps just the Qitou being too low than it is supposed to be
And a Qitou can be high or low actually, the style used in the promo pic isn't really that far from "accuracy", and that's definitely not Ming style as far as I can tell![]()
Just did a little bit more quick research, can't 100% guarantee the correctness but perhaps still solid enough
So, Qitou hair style is the typical hair style of Qing era aristocrat females, and during the early Qing period (when Xiaozhuang was alive), the most common seen style variants are:
Xiaoliangba (小两把, "double tiny handles")
Liangba (两把,double handles)
And the artist might be referring to this: