“Female” is well-defined for 99.99%+ of the population (and for most non-human species too, in fact). For those with DSDs, a judgement call can be made. For example, a person with XY chromosomes and the 5-ARD DSD (who was raised as a female due to the appearance of their external genitalia) has testosterone in the normal male range and thus is likely to have an advantage over females, and thus should not compete in the female category.

Cases of genuinely ambiguous sex are vanishingly rare, and are nothing to do with trans identities which are differences of social gender that do not change the underlying biology.