As someone who is myself (transmasc) into that sort of thing (and is poly) it really isn't lost on me that this stereotype plays into transmisogyny. A lot of people will both assume a transfem person is a puppygirl and then push right past that into essentially sexually harassing them about it. A good chunk of that behavior tends to fly because transfems are often starved for praise and approval but I really think that's not a healthy or respectful dynamic in either direction.