I 100% agree. For most of my undergraduate, the male-female ratio was a close to 40:60 (yes there were more women in my undergraduate maths classes than men, sample size ~400-1000). When I moved overseas to study Part III in Mathematics at Cambridge, the male-female ratio soared to about 95:5. This was the first time I was in an absurdly male dominated environment since my karate classes in primary school and I found it to definitely be more toxic. My experience thereafter has been the same: more balanced environments are healthier and less prone to toxic weeding of viewpoints.