Most female developers simply do not look as 'picture-perfect' as the one Toptal decided to use in their ads or at least not at work.
That particular photograph looks too staged and is not particularly suggestive that it was shot to be used in a technical career context.
Toptal chose an outlier to represent the majority and that is dishonest to the user population targeted by the ad.
Florencia, the developer pictured in the ad should've supplied different pictures or the company should've asked for them itself, preferably pictures with more work-appropriate clothing, like a t-shirt, shirt or blouse of some sort.
I seriously doubt any female programmer goes to work in that sort of attire, not only it would be over the top in 99% of the cases, it would be damn uncomfortable.