The last time I had this kind of surprise was with Audrey Tang, the developer of Pugs, an early Perl 6 implementation. Turned out she was not born female.
So, just by curiosity, I looked into the authors of this KaTeX thing. To my amusement, I guessed well : at least one of them is a trans[2].
There are certain kinds of IT projects in which women are formidably rare. I can't quite put my finger on what kind of projects I'm talking about, but let's just say it's a case of "I know it when I see it".
At some point we should consider admitting that there is something, I don't know what, that draws men towards this kind of projects much more than for women. And that this thing, whatever it is, may be a reason for the observed gender disparities in the tech industry.