It's very fair: YC bills itself as 'female founder friendly', if it turns out that you can't safely apply without your data leaking through to would be competitors that would be a serious problem. Note that there is zero proof for such a scenario but it is kind of odd that the OP applied there and that a YC backed company is now copying their business. At a minimum you'd expect YC to state very clearly that such a thing did not happen and that this is coincidence. That would put any speculation to that effect to rest.