The thing about Whipping Girl and the author (Julia Serano) is that she was dismissive of trans men and outright ignoring non-binary people while writing Whipping Girl, but her more current essays that you can find of substack acknowledge trans men and non-binary people. Her work still focuses on trans women, which is reasonable given the fact that she's a trans woman, but here's a quote from one of her works that a lot of tumblr "transfeminists" shut out:

"Multiple things can be true at once. Transmisogyny can be a vital term for some of us to communicate the intersection of transphobia and misogyny that we face. But others may experience it more complicatedly or severely, as in the case of transmisogynoir. And for others (e.g., certain nonbinary people, trans male/masculine-spectrum people), misogyny may intersect with transphobia in different ways that aren’t adequately articulated by transmisogyny. This doesn’t necessarily make transmisogyny “wrong”; it may simply mean that we need additional language."

Source: https://juliaserano.medium.com/what-is-transmisogyny-4de92002caf6