From a purely technical and legal point of view, the concept of a passport and other legally identifying documents should be able to factually identify the person that they are issued to.

This means that they should use accurate and current information that is clearly defined from a standard.

If I were a law enforcement officer in a resonable country, gender at birth is completely irrelevant, the current gender is highly relevant.

This however depends on what standard if used to define a gender in the paperwork, are they talking physical, so trans people would need surgery to have the paperwork changed, or are we talking about another standard?

In any way, this is like using the height of a baby at birth to identify the person at 26.

The medical knowledge exists, gender is no longer permanent, thus data about it can no longer be recorded as an immutable string, as that will introduce problems.

Given that there is a non-zero percentage of intersex people who have ambiguous or no genitals at birth, doesn’t this mean that they will be required to issue passports with X as the gender?