It's purely the weight coming off, losing facial fat is what creates that younger appearance, happens with any significant weight loss regardless of method.
I'm 70 and nearly back to being slim again, and I don't have a single new wrinkle aside from a couple faint lines near my neck. That whole "ozempic face" thing feels like something jealous people made up.
Facial puffiness really does add years to how someone looks, way more noticeable than most folks realize when weight numbers alone are all they're paying attention to.