I don't want to spend time on this topic, but fyi ...
A partial answer from Wikipedia Buddhism and sexual orientation -- Paṇḍakas
The paṇḍaka is a complex category that is variously defined in different Buddhist texts. In the earliest texts, the word seems to refer to a socially stigmatized class of trans-feminine and/or cross-dressing people, some of whom may have been sex workers. Paisarn Likhitpreechakul argue that these people are grouped together as special types of those suffering impotence due to seminal absence/deficiency rather than gender roles.
Paṇḍaka is categorized along with other stigmatized groups who are excluded from ordination as well; those with physical disabilities such as deafness or dwarfism, or those who have committed crimes. "The Story of the Prohibition of the Ordination of Pandaka" from the Vinaya claims that the ban is a response to the example of a paṇḍaka monk with a desire to have sex. Being refused by other monks, he had sex with animal handlers, who then told the wider community and brought disgrace upon the sangha.
So it's from Vinaya commentary, apparently, if you like to research that.
So that's why topics like What is a pandaka? revolve around wonering what the word "paṇḍaka" even means.
"Are you a paṇḍaka?" isn't one of among the questions asked at ordination, so I don't know at what point in the process the question even arises.
This overview of the Vinaya says on page 100,
The twelve equivalent p›r›jikas include the eleven disqualified types who should
not be ordained as bhikkhus in the first place. If they happen to be ordained,
their ordination is invalid; once they are found out they must be expelled for life
(Mv.I.61-68; see BMC2, Chapter 14 for details). They are—
- a pa˚˜aka (essentially, a eunuch or a person born neuter—see Saºgh›disesa
- a “non-human” being, (this includes n›gas, petas, devas, and yakkhas),
- a hermaphrodite,
- a person who poses as a bhikkhu without having been ordained,
- a bhikkhu who has ordained in another religion without first giving up his
status as a bhikkhu,
- a person who has murdered his father,
- a person who has murdered his mother,
- a person who has murdered an arahant,
- a person who has sexually molested a bhikkhunı,
- a person who has maliciously injured a Buddha to the point of causing him to
- a person who has dishonestly caused a schism in the Saºgha, knowing or
suspecting that his position was contrary to the Dhamma-Vinaya.
These eleven equivalent p›r›jikas apply to bhikkhunıs as well.
The twelfth equivalent p›r›jika, which applies only to bhikkhunıs, is the case
where a bhikkhunı leaves the Bhikkhunı Saºgha and takes up the role of a lay
woman (Cv.X.26.1). Unlike the bhikkhus, the bhikkhunıs have no formal
procedure for disrobing. If they leave the Saºgha, they are not allowed to
reordain for the rest of this lifetime.
A "parajika" rule is a rule for which the consequence is disrobing i.e. no longer being a member of the sangha.