My mom's name is Deane, funny enough.
Anyway, it's not the name, it's mannerism and/or appearance. Usually a mix of the two. One thing I've noticed is that a lot of pre-T guys are more self-conscious about their behavior coming off 'female' and put in effort to appear more male. Such as clothing, how you stand/walk, your vocal inflection and general body language. But then after some time on T, they think it washes away misgendering and stop paying attention to how they behave. Thus, they suddenly get misgendered when pre-T, they weren't.
Maybe that'll help.