On a post about Great Britains sex-based spaces laws that was painted as trans people being “banned” from public restrooms, I pointed out that they are not banned, they just have to use the ones that are for their sex.

Nothing incorrect there. 100% factually correct. Sex and gender are constantly spoken about as being separate things now, since sex is not changeable (despite what the person who replied thinks)
I was then permanently banned for “transphobia”:

Do they even understand what a phobia is?

YTA; trans women are women and trans men are men. Forcing them to use sex-based spaces based on the gender assigned to them at birth is not only an overt act of misgendering, but also puts such individuals at a far greater risk of harm given a far greater chance of standing out.
But there sex-based spaces like you said - gender identity has nothing to do with it.
The distinction between gender and sex in that context was retroactively applied to such spaces by transphobes who don’t believe in the existence of transgender people.
If the name were suddenly changed to ‘gender-based spaces’ would that suddenly fix the problem, or is there a reason beyond transphobes making no distinction between transgender women and men that transgender women don’t belong in women-only spaces?