Also the way statistics are collated with regard to born men and women.
E.g. if company boardrooms must comprise, say, 30% women at minimum, but those "women" are actually transwomen who transed in their 30s after climbing the greasy pole as men..... then the statistics may bear out - women represented, tick - but if those "women" are actually transwomen, then no - women are definitely not represented.
Women's scholarships and bursaries, in order to try to redress the traditional pressures against women's education. Again, if such scholarships or bursaries are given to female-identifying males, then that's another woman who was unfairly robbed of an opportunity she could have had.
Let alone crime statistics, and sex crime in particular. If transwomen are recorded as women, for crime recording purposes, then if self-ID becomes legitimate, we can expect an explosion in crimes, especially sex crimes, committed by women, and a reduction in such crimes committed by men. All false. Who wins in this scenario, eh?