The information is easily acertainable and it is well understood how DSDs arise see here: https://static1.squarespace.com/static/6337427dc583e5578b5d2192/t/65c8ee1210f5ea02e0cdaabb/1707666963838/Sex+Development+Flow+Charts+2024.02.11.pdf
If a baby is born in a place with access to chromosomal and genetic testing any hint of ambiguity of the genitalia would be thoroughly investigated and it would be worked out what was going on. The issue is in poorer places with poorer access to healthcare of religious or political regime considerations where they will assume, rather than test. Why do you think the 5ARD athlete have all been scouted from poorer backgrounds? There are no controversial XY males in women's sports from N.A or Europe.
These are also people in their 20s and 30's born several decade agao when genetic testing was still expensive and time-consuming and only available in specialized labs. That is no longer the case. Every hospital now, pretty much, can process a cheek swab or other sample to look at chromosomes under the microscope and determine whether XX, XY or some abnormal number of pair 23 sex chromosomes are present. The number of babies born and wrongly assigned sex or not noticed that there was a DSD must be vanishingly small, even in poorer countries. Babies not born in hospital, yeah maybe, but it certainly isn't unknowable. And any parent notcing that their daughter doesn't menstruate at puberty must, now, even if they deny it to themselves, know that something is up.