Same-sex attraction isn't an illness that needs to be cured.
"Unwanted same-sex attraction" is a misnomer. People internalize negative beliefs about their identity and attraction, not because these identities are wrong or bad, but because they face stigma, discrimination, and prejudice that communicates to them that their feelings and self are shameful and wrong. That is what conversion therapy does--it reinforces negative meessages about being LGBTQ+, being who you are and were born as.
The goal of any mental health professional should be to improve mental health and mental well-being. Strong, empircal, peer-reviewed evidence suggests that conversation therapy does not work. Not only is it largely ineffective in "changing" an individuals romantic or sexual attraction, but it has been found to more likely cause harmful effects rather than improve well-being. Ban conversion therapy.