What does that mean effectively? For instance let's say a gay child is being bullied in school. Should the teacher pretend not to see it? Should they not talk to the bully about treating others with respect? As a father and grandfather I recognize parents should have the only say (barring a court order) in the upbringing of their children, but it you loved your children, why wouldn't you want teachers to be able to comfort them and reassure them in those moments?
I don't have a problem with comforting and de-escalation, but what is often done in some schools is propagandizing about gender identity.
Children are highly impressionable, which is precisely why certain activists in the LGBT lobby target children. It's a numbers game for them. They pretend it's a matter of encouraging people to come out of the closet, but in reality, it's grooming when done to children.
What the left is reluctant to admit is that sexuality and gender identity are highly environmental and socially influenced. This is shown throughout history by cultural differences.
For example, we don't consider pedophilia to be acceptable, but it was acceptable for the Ancient Romans and Ancient Greeks. This was possible due to normalization of pedophilia by those cultures. By the same token, our culture took measures to stigmatize it.
Gender identity and homosexuality are no different. Influencing society to be more accepting of homosexuality, gender dysphoria, or non-binary identities for adults is one thing. Encouraging it among children is quite another.
Young children can go through strange phases for any number of reasons, but it's not usually a matter of gender dysphoria. And even when it is gender dysphoria, puberty blockers are an extreme measure that should not be taken 99% of the time. Sex reassignment surgery is completely absurd to perform on a young child as well.
But ultimately, this has become an issue because the LGBT lobby sees the power in converting future generations to their group. It's no different from what you'd expect from a political or religious group, but the consequences are far more severe.