Multiple definitions of feminism exist:

The notion that people of all genders should be treated equally
The notion that women are particularly poorly treated
The notion that there are structures that cause people of different genders to be treated differently
The social political movements around these ideas

Key Concepts

Our community is majority male, which means that things tend to be communicated in a way that men tend to prefer engaging with. It’s easy to think that discourse is “epistemically better” when instead it’s “how groups of men like to talk about things”
It is tiring to think about whether people are talking to you because you add academic value or because they fancy you. And if this only happened once it wouldn’t be so bad, but if it happens all the time, it quickly becomes draining and contributes to imposter syndrome.
Because this community assumes relatively high levels of trust towards strangers, women generally don’t expect manipulative behaviour. So when this kind of behaviour occurs (if by accident or deliberately), it takes people to longer to realise/more vulnerable and feels like a betrayal of trust.
It is possible that the rationalist community isn’t immune to a tendency of associating attractive women with lower IQ’s/skill levels.
The potential cycle of “less women are into rationality than men, and thus, rationality will be less women-friendly” might be a vicious cycle