I believe her.
I'm generally what's considered to be a high achiever (academically and sports) and happy enough with where I've got to, so this isn't some sort of sour grapes.
(I mean I have the paper results to show I do make the effort and aren't afraid of putting in the work and getting results. Definitely not a snowflake!).
However, there are often sports coaches and teachers who target some people arbitrarily - angels to one student, devils to others.
I've borne the brunt of these and looking back, I did nothing wrong - I was and have always been respectful and hardworking and willing to learn - they were just sexist bullies taking advantage of a power dynamic.
They decide they don't like the look of someone or want to break them mentally, and then it's all little bits of spiteful criticism dressed up as "training" and "tough love".
Look at all the gymnastics bullying situations. Were all of those children/teenagers "spoiled brats" not wanting to put the work in? I don't think so.
Some people just get a kick out of being nasty to females with a small amount of power given to them. But they'll be angels to others.