Using the following features, for reference:
Eyebrows - 2
Eyes - 3
Nose - 5
Mouth - 3
Jaw - 2
I took comparison screenshots with various lighting from both the Endwalker and final Dawntrail benchmarks, and have tried to match the angle as best as possible.
The biggest point of contention for me is without a doubt
the mouth.
Link to image slider comparison
Overall, the mouth seems to have been made much narrower. The definition between top and bottom lip has been softened, removing much of the cute cupid's bow appearance. The dimples have been completely obliterated, and the mouth corners overall seem to have been greatly softened. The transition from lip color to skin is far less gradual and now very sharp, which diminishes the mouth corners even further.
All of this contributes to the narrower appearance, and gives her resting expression a sharper, meaner look. I am sure I'm not the only face 2 player who chose their face because it had a softer appearance, so this change is very jarring.
And... the smiles. I used to
love seeing her smile, it always had a very gentle but mischievous air to it. Now... I don't even really know how to describe it, but I genuinely flinch and try not to look whenever cutscenes have her smile. It has a very forced and uncanny look to it, likely a result of the narrower and sharper appearance of the mouth overall.
Dawntrail's creepy tiny-mouth smile vs Endwalker's softer one...