When you think about it it is quite incredible how much bother this stupid word "gender" causes. IMO it is blindingly obvious that gender as a concept is 100% social construction because it's a word that doesn't have much of a meaning and it means different things to different people.
For feminists gender is a social order, it is political, it is a binary class system and can be analyzed according to Marxist political theory.
For genderists it is an undefinable (and therefore unchallengeable) individual inner essence.
For some people gender is simply a synonym of sex.
I think it has become a word that feminists should stop using because most people don't realize that we are using it to describe a system of social order. I prefer to use "sex caste" as coined by Sheila Jeffries because it is a much clearer term.
This word gender has got us in a whole load of trouble because when genderists use it they are generally actually talking about reproductive sex but they use gender in order to obfuscate because otherwise it is just too obvious that they are spouting nonsense and that the emperor has no clothes.
If people were to talk about an "inner sex identity" or a "sex spectrum" or being "sex fluid" it is obvious that they are talking claptrap because everyone knows what reproductive sex is and we know where babies come from.
We really should resist the word gender altogether (especially as trans ideologues consistently fail to define what they mean by the word despite it forming the basis of their ideology).