While USSR technically had gender equality, reality was very different. For example, how much of The Party elite was women? Virtually none :) Sexism was through the roof too.

IIRC the "less equality = more women engineers" example was India. And USSR was somewhat similar to modern India. On paper women were on par (= purely technocratic acceptance to universities) but day-to-day life was different. "Pursue your passion" was not an option. So if a girl was smart in maths, engineering it is. Fatherland needed engineers, not people in BS studies who'd work in Starbucks afterwards.