I joined a company as a new employee new to the industry with another girl at the same level. She left literally only months later. A good portion of it is that a lot of women don't find a career sitting behind a computer all by yourself in your room writing code and just weirdly no-lifing like men do very fulfilling. Or working in the guts of a backend system where your changes will never be seen. Or spending so much hours learning a ton of different technologies & methodologies constantly. I myself do plenty of study outside of hours to upskill & keep up, and many days constantly struggling to get my thing to work and feeling pressured. She was also less assertive and didn't reach out to ask for help, or when something wasn't clear she wouldn't set up meetings, she also wouldn't ask for what she needed or make noise when she didn't like an approach or want to do something else. We really want women to join and we accommodate really well, just women are not very inclined to careers like this. Of course she's only one person, we have plenty of other women who do very well too.