What you want to ban is any kind of therapy which might help a distressed and vulnerable person accept themselves as the sex they are and actually live a semi-normal, or even completely normal life.
That's not conversion therapy.
Unfortunately people who transition cannot live a semi-normal life.
Almost none of them convincingly pass.
The occasional tall and muscular trans man may pass superficially as a man in order to use men's toilets unnoticed, but they cannot use urinals, communal changing rooms or showers or wear swimwear without outing themselves. Without a penis they are excluded from truly "living as a man" and their dating pool is realistically restricted to lesbians and bisexual women who don't mind referring to them as though they are men and essentially pretending to be in a heterosexual relationship. Neither gay nor straight men are likely to be interested. If they go so far as to have a phalloplasty they will most likely be plagued with awful health complications.
Trans women are even less likely to pass but may fare better in dating terms if they are attracted to other trans women, or men who don't like to acknowledge that they are gay or bisexual, or if their pre-existing female partner decides to stick by them post transition. But almost nobody considers them to be women, and using women's single sex spaces (now confirmed to be illegal) will be a constant source of conflict with the female users of that space who do not accept them, even if they are too afraid to challenge them.
With all this in mind, who would want to be trans? Surely it is better not to be?
If you're so sure you would still be trans no matter what talk therapy you had, fine. Have all the talk therapy and prove it. And let others have all the talk therapy in the hope that for them, it leads to a different and better outcome. One in which they learn to accept themselves for who and what they are (i.e. a member of their own birth sex, who may or may not be same sex attracted and/or neurodivergent), rather than engaging in a life long battle to change everything about themselves in the futile pursuit of an impossible goal.
I do not say this to be unkind. But Helen Joyce was right. Being trans is an adverse outcome, and making changes to your body to resemble a member of the opposite sex should be an absolute last resort, once all other possible explanations for your distress have been explored and discounted, and all attempts to reconcile you with your actual biological sex have failed. The number of "trans people" should be kept to an absolute minimum, because it is, by most people's standards, not an ideal way to live your life.