@Shizuku
The Trevor Project, who authored the study in the OP, are not some random bunch of statisticians who just cobbled together a quick study about LGBT people without really knowing how to do it, they are an American non-profit organization founded in 1998 focused on suicide prevention efforts among lesbian, gay, bisexual, transgender, queer, and questioning (LGBTQ) youth and have ben studying sucidality in LGBTQ youth for 23 years - they are world experts on the subject and have done multiple studies over many years.
en.wikipedia.org/wiki/The_Trevor_Project
So they are not so easily dismissed. Nor is the fact the study was done in the USA - there is no logical reason to think that conversion therapy harms US trans kids but not UK trans kids - it's the same condition having the same "treatment" applied.
Nor can you discount it as being too old - it was done in 2019 - just over 2 years ago, and there is no logical reason to conclude that conversion therapy was harmful for trans kids in 2019 but doesn't harm them at all in 2021.
So at this point, the study remains the best evidence presented in this thread for the effects of conversion therapy on trans kids. If you support removing the T from the proposed legislation on conversion therapy, then your claim to be concerned about the well-being of trans kids is empty.
shizuku, no-one is trying to discredit the Trevor Project. The report presents data from a large number of LGBTQ young people in the US, and there is no reason to think that their survey was not well-designed. But the fact remains that their data
as presented in the report do not support the conclusions you are trying to draw.
All that the data you link to in you OP show are that some US trans and nonbinary young people attempt suicide after intervention that is classified by the data-collectors as conversion therapy. That's it. That's the extent of the evidence in the report.
There is no way to check that the rate of suicide attempts in this group is higher with or without conversion therapy, because that information is not presented.
There is no way to determine whether the suicide attempts reported in the conversion therapy group were caused (directly or indirectly) by the intervention, because not enough information is supplied in the report, nor are any statistical analyses reported that might support that conclusion - e.g. by showing that suicide attempts were more closely associated with conversion therapy than with other mental health diagnoses, or age, or educational attainment, or socioecenomic disadvantage, or neurodiversity, or length of time since transition, or level of social/familial support, etc.
There is no way of knowing whether survey results obtained in the US, where legal protections against discrimination, access to healthcare and religious demographics are very different, are applicable to the UK.
There is no way of knowing whether the results from this self-selected group of participants, recruited via social media, are representative of all trans and nonbinary young people in the US, et alone elsewhere.
It isn't evidence of the effects of conversion therapy, let alone "best evidence".