Gender stereotypes- sex stereotypes
See, that's not straightforward either, because surely gender is a sex stereotype?
This is something I've turned over in my mind for many years, not just since transactivism became a thing.
When an unknown man walked into the office and spoke patronisingly to me and my female colleagues, then made a beeline for the only visible male colleague to have his Serious Conversation, was this because of sex or gender?
Patronising Man was not interacting with my biology. He was interacting with his idea in his head about what men and women are and do.
So he was reacting to gender. What's more my gender was a construct in his head! Didn't matter what I thought or felt or how I behaved!
However, he had attributed that gender-construct-in-his-head to me, because he had identified my biological sex as female and therefore applied his Gender = Woman label. So it was indirectly because of my sex.
I'm never sure whether to use "sex" or "gender" when talking about circumstances like this.