I don’t trust anything these days, and this sort of appeared out of nowhere, so caveat surfor.
It is one of three things
1. An outtake from the promotion for Sydney’s “Birthday” line, with an escaped nipple
2. An AI fake created to look like that.
3. A legit image, but with no nipple. Based on the angle, that could be a finger from her other hand.
I don’t know, but here it is:

That’s her other arm holding the cake
That would be my vote as well.
Gee, if only there were a picture of her actual nipple available somewhere we could use as a comparison.
That bit of sarcasm out of the way, I’m flummoxed as to how anyone could think that’s anything BUT one of the fingers on her other hand.