What is the appropriate response if a fellow woman pulls you aside and says "Go easy on this code review, she is a woman after all and already gets a lot of shit."? Of course it is "Sure, this will be my friendliest code review ever!".
Wait, what? Shouldn't we treat all people equally? Why is she asking me to make an exception for her?
The first problem is that we treat people differently if we know that they are a woman for example. This is called unconscious bias and there are numerous studies that our judgment changes as soon as we know we are looking at the work of a woman.
Unfortunately this happens unconsciously, but we can make ourselves aware of that and counter the effect. Try to go the extra mile of friendliness. Be extra polite, extra professional, extra supportive. That should make up for the bias gap and bring your code review to the same level of fairness as you would do for a man.
Harsh code reviews
If somebody asks you to go easy on a code review it means that you usually don't go easy on a code review. So there might be a problem in general with your code reviews. Are you harsh for no reason? If I read your code review do I feel appreciated or do I feel embarrassed? Tone of language is key here and also thanking them because they want to make a contribution after all. Are you just picking on some details, but the approach they took is fine? Tell them that: "Your approach looks good and I would do this the same way, here are just some minor nitpicks ...".
Be patient - people might be new and just starting out on the project. Sometimes it might feel that after all the time that you spent on code review you could have written it yourself by now. But teaching people is a powerful concept, you are sort of cloning your skills into their brains. This will pay off many times during the lifecycle of your project.
She already gets a lot of shit
Please believe that. The amount of harassment and annoyances women and other marginalized people receive is well documented. Reacting to that with "But I will treat all people equally!" makes you at least look ignorant, it might also make you a silent bystander to unfairness going on. Treat this as a serious warning sign - somebody brought up problems directly to you.
You are approachable
The good news: it seems you are not a total jerk and people trust you enough to talk to you about this. They are confident that you might listen and help. They appreciate you. You have the opportunity to listen and understand what is going on, which also means that you suppress any immediate knee-jerk reaction. You want to be supportive, right?
With that in mind we can even improve our response to "Go easy on this code review, she is a woman after all and already gets a lot of shit.": Sure, this will be my friendliest code review ever! Let's also talk again later what we can do to stop all the shit she is getting.
P.S.: Oh yes, I'm probably also doing some awful code reviews, so I'm also addressing this to myself.