When I did my BSc in CompSci (2000ish) there were around 10% women at enrollment, and down to 4% at graduation. It was kind of sad to me (male), and part of the reason I delayed joining the industry.

It seemed like a cultural issue to me, like it was just too boyish and bro-ish for women to want to enter the programme. Sausage party effect.

Judging from the department photos of graduates from past years, you could see that there were way more women in CompSci the 70s and 80s.