Assuming you’re asking in good faith, “Fair enough” is what you say when someone counters your opinion with theirs, and you are saying that you’re going to agree to disagree. Using that phrase when a woman has corrected your factual inaccuracy is acting like everything women say is “their opinion.”
Oh I can see how annoying that is. I’ve used it when I’m conceding a point in a discussion on which I still disagree on the subject overall. Regardless of gender. But I imagine I might be in the minority here.
I get it. I don’t think anyone’s suggesting it’s the case every time someone uses it. If someone uses it with me, I don’t automatically assume they’re a male supremacist. But when dudes keep using it with women in a specific type of situation, yes, it gets annoying and seems extremely condescending.