It seems to me there is too big a difference between trans and LGB for it ever to be practical to have a 'one size fits all' approach. I am glad to see this split.
Why? ...
To be gay is just to feel attracted to people of the same sex. And to feel attracted is to be attracted. So if I feel I am gay, I must be gay. It would be invidious, then, to think of asking someone a child, say, who sincerely feels she is gay whether she is really gay. The question cannot arise because to feel attracted is to be attracted, so to think one is gay is just to be gay.
It is different with trans, as detransitioners illustrate. If I feel I am trans, it might be that I am trans ... but I might be making a mistake. (Keira Bell, for those of you who know the case, illustrates this possibility with utmost clarity -- someone who wrongly thought she was trans and regretted the choices made following this mistake about herself.)
So, particularly for children, it is really important to understand that feeling one is trans is not the same as being trans (unlike, to reiterate, the way in which feeling one is gay is, precisely and exactly, the same as being gay).
It follows from this that there needs to be caution, in particular, about children. Asking questions and discussing feelings around the subject and veracity of a child's self-description as 'trans' will always be called for and is to be encouraged, in a way that discussing the veracity of a child's self-description as 'gay' would be out of the question (and, in the extreme, to be banned as a 'conversion practice').
Of course a lot of people trans people included have not understood this, which is one of the reasons the 'T' got to be linked with 'LGB' in the first place. People say things like, 'Take me as I am' ... 'Surely I know my own identity' and so on. Some things, indeed, we know for sure about ourselves; however some things we think we know about ourselves and this is particularly true of children turn out to be mistaken.
There definitely is a difference between a self-description as gay, which must be true, and a self-description as trans, which might not be true.
[To see this distinction with the heat taken out, so to speak, think of someone self-describing as 'hungry', and compare with someone self-describing as 'wonderful': 'I am hungry' must be true if said sincerely (because, again, to feel one is hungry is to be hungry). However, 'I am wonderful' may not be true, however sincerely claimed, because to feel one is wonderful is not necessarily to be wonderful. In this respect, 'gay' is like 'hungry', but 'trans' is like 'wonderful'.]
In short, then, T is sufficiently unlike LGB as to require a distinction about 'conversion' practices.
[Oh, and just for the record. There is nothing transphobic about this. None of this derogates in any way from the rights trans people have to live their best and fullest lives however they see fit, which I support to the fullest extent possible. (Thought I better say that, just in case!)]