A lot of people would just put they are a writer of both if the options is there, even if it's not entirely true.
If the question was "who do you write?" and if the answers were "male" "female" "non-binary" and "multiple/all of the above," then every single person here would say "multiple/all," and we wouldn't have any information about who we write about more. Hence, the question was "who do you write the most?" instead of "who do you write?" In my Doctor Who fanfic, my ensemble cast of protagonists didn't have a clear hierarchy of who controlled most of the action, but from the 5 characters whose POVs we saw, the split was Woman (20,000 words) Man (15,000 words) Woman (12,500 words) Man (8,000 words) Man (7,500 words) And my Urban Fantasy WIP is also female-dominated, but in exactly the opposite way: the POV is dominated exclusively by a single male narrator, but there is a clear hierarchy of which protagonists control most of the action: Woman Man (narrator) Woman Man I do have a lot of major male characters in my work, but I still felt confident in voting "Male author, female characters"
So by skewing the pole you wind up with flawed data to fit your preconceptions of what you want to prove... i'm out
For me, it used to be pretty 50/50, but lately I've been writing a lot of male protags. There's really no reason why.