California wants to ban books about changing an individual’s sexual orientation.

Is this you claiming that the only harm that attempted gay conversion therapy is is heightened anxiety?

Not sure the second part of your sentence, there. The only way I can see to parse it is that if a demographic is used to being persecuted, then continuing that persecution is acceptable?

No, they’re not. They’re allowed to engage in practices or sell products whose efficacy may be controversial, but they’re not allowed to engage in provable dishonesty and outright fraud. Take a look at some of the advertising in old magazines from, say, the 1930s. They’re full of “miracle” cures and devices that don’t work. Most such advertising would not be allowed today. It’s not “censorship” and it’s not “book banning”, it’s good riddance to fraudsters preying on the gullible.

Banning fraudsters and con artists is not unconstitutional. It’s part of the function of responsible governance.

I’m seeing more than that there:

*The potential risks of reparative therapy are great, including depression, anxiety and self-destructive behavior

Evidence shows that the practice may actually cause emotional or physical harm to LGBT individuals, particularly adolescents or young persons.”*

Also many mentions that various associations found the practice to be harmful without going into specifics.

I would generally disagree. Unlike gay conversion homeopathy isn’t in and of itself harmful, its just ineffective. This is the reason the FDA doesn’t bother regulating homeopathic remedies. As long as the inactive ingredients aren’t toxic they know there won’t be any harmful side effects.
Gay therapy on the other hand isn’t just ineffective, its outright harmful.

If a trainer of seeing eye dogs decided to drum up buisness publish a book “20/20 vision in 7 days”, that has as its first step using concentrated hydrochloric acid eye wash, I would hope that those people who went blind following the would be able to sue him.