@Thehawki The reason cis is offensive to many women, particularly feminists is because of the nature of the term gender.
The word gender has taken on a new meaning because of extreme transactivism. It's meant to mean an internal essence that tells you whether or not you are a man or a woman, completely separate to biology. This doesn't really hold up, because being a man or a woman is a description of biology.
Before transactivismism, gender, as a sociological term, meant masculine or feminine. A set of stereotypes based on societal ideas of what constituted masculinity or femininity. In fact, even trans organisations called it the same thing. Until extreme transactivism tried to pretend that men who wanted to be women were actually women.
And the issue is, of course, that society will determine masculinity and femininity through a sexist lens.
So femininity will be things like fragrant, nurturing, weak, compliant, sweet, ditsy, a follower.
And masculinity will be things like dominant, strong, leadership, logical, rational.
In terms of feminism, gender has been used to strip women of any power. Women were considered to be too ie responsible to vote, to empty headed to educate to degree level, too unreliable to have their own bank account or get a mortgage without a man's co-signature.
And in fact, until 1992, rape within marriage was completely legal, because society deemed that women's legal duty was to provide men with sex. That was their gendered role.
gender, for women, meant they were irresponsible, unreliable, empty headed, and must be available for sex.
The saying goes that women are oppressed due to their biology, and gender is the means by which it's done.
So you can see why many women, particularly feminists, do not find it acceptable to be called cis. Because the last bloody thing they do is identify with the gender that society wants to impose on them. The whole point of feminism is to break out of gender roles, not concrete them in.
Hence 'gender critical'.