there is an easy easy ( although not a very popular ) explanation)

Neither the right, nor the left, give a flying fuck about LGBTQ community and their rights… what they both care about ( and the only thing they care about, is votes)

so, taking into consideration that there is a relatively small percentage of LGBTQ people, compared to the rest of the population- the support of the parties depends on how their voters feel about a certain issue- For as long as most of the democratic voters are pro-LGBTQ rights, the party will appear to support it, not because of the LGBTQ community ( there is not enough of you to make a difference in the ballot) , but because of what the voters want…

But, if, the feeling with the majority of voters starts to change- or, if they simply stop caring as much about the issues of “non-binary” individuals, then, even the biggest political supports of the LGBTQ community will change their tune in an instant and switch from the ones supporting your rights, into the biggest homophobes the planet has seen , with the speed most of us will find difficult to believe…

don’t make a mistake and expect anything else from anyone, on any side of the political divide