It's blatantly obvious to me, but I've been collecting her signatures for years and have accumulated a collection ranging all of the periods of her career and signing styles.
This simply doesn't fit any style of hers. Also, she is left handed and her signatures have a noticeable downward slope. I don't want to give too much away on a public forum, but another thing to know is that she crosses her "tt"s with a mark from the right to the left. This one is left to right.
Also, I have never, ever seen a Pop figure that she signed. She is tough signer to begin with, and when she ever does it's usually photos.
Really useful. She's actually the last signature I need for my collection hence I was even considering a GA certification. I will definitely look out for those mentioned traits on her autographs from now on. Thank you!
Good luck, and expect to pay a lot for a real one. There are over 160 items on ebay right now and about 10% of them are authentic (and that's a higher percentage than usual).