It’s not a matter of ability, but instead comes down to a numbers game. There are significantly more men who play chess, so they will be overrepresented at high levels of play while women will be underrepresented.

You see it in many, many non-physical sports. Chess, e-sports, professional poker, etc.

It’s anecdotal, but I myself used to participate in a niche board sport at a professional level. The skill gaps between men and women at the top level is enormous. The boards are electric, so there is little physical sex based advantage, if anything women’s lower centers of gravity is a plus, but there are just significantly fewer women who race competitively. This is evidenced even further by the fact that each of the women at the top level have tremendous skill gaps between one another when compared to the men.

Ultimately, the more competitors you have in any given bracket, the higher the skill ceiling will be pushed.