I would describe it as like emo pop but with all the punk influences of emo kind of filtered out. Emo pop isn't new but most of the artists are from a decade ago and still has the punk influences there so zoomers aren't gonna be fully aware of all the different takes on the style.

Billie Eilish's "stereotypical fans" (for lack of a better term) would be zoomer white girls, they probably like the bright colored hair and lazy looking style she has but aren't allowed to do those things because they still have to go to school and all that kind of stuff. I had purple hair for a while and I would get compliments all the time from people who look super normie, so I think a lot of people wish they could be a little crazier in what they wear and stuff but are restricted by their jobs and stuff so they see people like Billie Eilish and think "man that looks cool, I wish I could be like that but society won't let me."