There’s nothing wrong with recognizing that LGBT people exist. What’s wrong is using psychologically and emotionally manipulative psyops essentially on kids. There certainly should be resources for teaching about LGBT people and helping LGBT adolescents to understand themselves, but this is not what’s happening in schools.
It’s true that they are not taught in k-12 schools - actually, the are ‘practiced’ in k-12 schools. These are concepts which are not taught, but practiced. This is why it’s called Critical Race Praxis. I am citing this book: Envisioning Critical Race Praxis in K-12 Education Through Counter-Storytelling (Educational Leadership for Social Justice)
To understand all of this, you’d want to read the books Critical Race Theory: The Citting Edge, by Richard Delgado and Stephen Stefancic, Words that Wound, Excited Speech by Judith Butler, Gender Trouble by Judith Butler, to some extent White Fragility by Robin DiAngelo (which is more “pop CRT/Whiteness studies” but still has influence), Curiouser: On the Queerness of Children by Hurley Bruhm.
There’s a lot more books than these that would need to be read, but they ultimately all uphold an illiberal ideology at least, and they often advocate for some kind of socialism. And, while there is a lot of good information in these books, other positions which these books suggest sound unhelpful or bad to me.