I saw a female person with shaven hair and a bright button up shirt today and instantly assumed her them/they pronouns.

Was the top button done up?

Dang is this a they/them thing too :D I love to button all the way up

I don't know if they still do it but it's definitely a trend I noticed they partake in. These trends (some of which I also partake in, like the hair colours) are just fashion rather than uniquely "non binary" though. Nonbinaries are noticeable because they're slaves to fashion and base their entire lives around it, starting with the concept of "gender identity".