Yes, there definitely is a bias and if you're a man, your posts will most likely be scrutinised through that filter and you won't get away with saying things that a woman automatically would. For example, I posted on a thread in the Sex topic about some underwear with the obviously male poster wanting to know what was included. He was berated and the thread deleted. I posted on another thread in the same topic about a sex toy and that's fine apparently. Threads should be judged and deleted on 'merit', not because of the sex of the poster.
That bias though is, I suspect, because it's always been very much a 'man's world' and most, if not everything, is set up for the convenience of men. That's a positive and enduring bias in your favour right there. You're also posting on a site that is predominantly made up of women which means that the filter here is unmistakably female and understanding is therefore easier for women. Also, often less jarring.
That said, I've come across some dreadful women on this site who I wouldn't want to know in RL, but I post here because that's tempered with some truly awesome posters (most actually), who offset the nastiness and I love posting alongside them.
So, you're not wrong about the bias but if it bothers you then pick a different name so that assumptions won't be made about you from it. It's not difficult to do that and it will remove any instant judgements of 'mansplaining' or jumping to conclusions about your motives for posting.
Up to you but, if you post like a man and you have a username that sounds as if you are a man, you'll be treated as one and, from what I've seen, it won't be positive, it will be - at best - tolerated.