I thought so too at first, but zoom in to where the neck joins the head. What looks like the head’s shadow from a distance is actually a hard seam between thick neck and thin neck, with much of the apparent shadow actually a cutout showing the background.

Looks like the Seedream result here has been changed to fail, which I’d agree with, too. Pose change complaints aside, I think that neck is actually the same length were it held straight.