Ok this is where I admit it gets tricky and vague. I cannot bring myself to dissect a person with lines and arrows a la Perez Hilton or those plastic surgery sites (and I know you didn't ask for that), but I think there's something in the forehead/brow, and kind of a blockiness overall in the face. https://soapdirt.com/i-am-jazz-spoilers-jazz-jennings-scary-post-surgery-pop-second-operation-needed-asap/

Jazz simply looks like and reminds me of a lot of boys I've known who do present as masculine/male. I see a lot of it in candid photos as opposed to posed pictures.

I'm not trying to slam Jazz's appearance. This is a very feminine-presenting person, and I don't think everyone should get to one side like you're Barbie or Ken. But something pops for me, even in earlier-transitioning youth (like the Sports Illustrated model). It's ok, it is what it is. It's just that subtle thing.

I googled Valentina Sampao last night, and similar issue. Pap photos on the street or runway--looks male. Posed modeling photos--very female. Again it's in the brow and blocky face. A lot of men causally frown in a way that intensifies it and makes them look angrier than a woman intentionally frowning imo because of that heavy brow.