> The idea of the "existence" of a trans person is subject to debate. There are a significant number of people that believe that "being" trans is actually not something of substance, that it is "all made up".

The political debate is about language changes (e.g. "LatinX"), access to sex-segregated spaces, participation in sex-segregated sports, what to teach young children, etc.

> Bostock was a ruling about sexual orientation, not about gender.

Bostock involved multiple consolidated cases, one of which specifically involved gender identity.

> I think if you are citing the 2020 PEW poll on this topic it is probably quite obsolete as it seems clear that the partisan valence of this issue has changed quite a bit very recently.

No, the issues have changed (see above). This is common and unsurprising. People are generally a lot more accepting of civil rights than attempts at social engineering, especially social engineering directed at children.