Tl;dr media representation of Bisexuality focuses on sexual and gender fluidity so women are more "masculine" and men are shown as more "feminine" and Bisexual people will often follow these archetypes and subcultural cues
IMO I think a lot of bisexual representation focuses on representing the fluidity of both sexual and gender expression, hence why many bisexual women are depicted as doing traditionally masculine-oriented activities in media or at least doing things considered "unladylike", like getting tattoos or weightlifting or wearing "masculine" clothes like denim or leather jackets; Rosa Diaz from Brooklyn Nine-Nine comes to mind.
Similiarly, for men, I think there's a focus on representing bisexual men as having a "softer" or more "feminine" side in addition to a masculine side, though I think that's also true across the board for all men on the spectrum of queerness. Representation of bisexual men in media is pretty piss-poor even when considering the rampant fetishization of bisexual media, but most of the big bisexual male celebrities and characters that I immediately think of- Alan Cumming, William Shakespeare, Mads Mikkelsen's exceptionally dandy portrayal of Hannibal Lecter- have a distinctively effeminate admixture with their masculine side.
Personally, I'm very masculine and outwardly straight-presenting. I drink energy drinks and pre-workout instead of coffee, I lift every two or three days, I used to play electric guitar and listen to a fuckton of Metal, I dress in clothes that accentuate my musculature, I'm in a very male-overrepresented profession, and I tend to read non-fiction over fiction. Most of my "feminine" side is often hidden to activities like the occasional Botox treatment, high-end skin products, and owning a bidet (since the topic of if wiping one's own ass makes one gay has become another front in the culture wars, apparently).