Many (most?) events aren't separated by gender, but most games will still be man vs. man. Men outnumber women in chess by almost 6:1. At higher levels, the ratio is more extreme (something like 40:1).

There are women-only competitions to encourage more women to play and to give them some visibility, but it's not the same premise as separated sporting events, that women have an inherent disadvantage.

There was a lot of good discussion about gender in chess a few years ago when Queen's Gambit was released on Netflix[1].

1. https://theconversation.com/whats-behind-the-gender-imbalanc...

Or maybe they're just trying to do the right thing for women. Perhaps the decision-makers in FIDE have listened to feminist critique of this recent policy movement that advocates for men who call themselves women to be allowed in what would otherwise be women-only spaces.