Hmm I think it just might be the angles used (her forehead looks a bit bigger in some places) , how open/tense her eyes are depending on the scene, and whether she's making a funny face.
Because I was gonna agree and say her face looks rounder, but really if you look at the face foward shots in 72 (pg 33 on the official) and 73 (page 5), they look very similar other than her expression being different
Her outfit is def a bit poofier though
So really the artist just may have had a break so there are slight differences

What happened to the art style from chapter 72 to 73 like Aaron looks prettier but Regina and the other female characters shown in this chapter look wrong. Regina looks more petite and her face is all kinds of off. The shape of her head is different her eyes are wider her mouth is smaller and her chin is a lot thinner. Was there a change in artist or a change in style.