Puberty blockers are also used in cases that don't involve trans people. So are they magically safe for use in this instance then? They can't even follow their own argument because they're BLINDED by hate.
They are usually used to treat precocious puberty - which is to say, they are used only for a short period in cases where puberty begins 'too early' (so before the age of seven for girls, eight for boys) and then come off them when they hit the 'normal' age for puberty. So the point they tend to make, and that the Cass Review made, is that there isn't enough evidence regarding puberty blockers when used to treat older children and teenagers over longer periods of time.
With that said - its fairly clear that there isn't actually a lack of evidence on this at all! A while back I reviewed a paper from Yale which made an evidence-based critique of the Cass Review. The University of York systematic review that provided the backbone of the Cass Review was heavily criticised for its unorthodox approach to reviewing the existing evidence. They are interested in the long-term impacts of puberty blockers, but excluded all studies where subjects went on to take hormones. Which is to say, they excluded the vast majority of studies because the vast majority of people who take puberty blockers for gender dysphoria/incongruence go on to take hormones. Because they are trans!
The new Randomised Control Trial has come following Cass's assertion that there is a lack of 'high quality' evidence - by which she means there isn't enough evidence generated by Randomised Control Trials. There is good reason why Randomised Control Trials haven't been favoured in this area - the main reason being that it is quite rapidly obvious who is and is not in the control group based on whether the markers of puberty stop or continue to develop. It is also worth noting that a decent number of treatments currently in usage by adults and children alike across a range of conditions lack of standard of evidence demanded by this review.
How things are currently playing out is a classic example of the constant goalpost-moving by the transphobes, meaning either that trans people can never win (see: trans women being criticised for looking too much like men, and then criticised for 'parodying womanhood' when they try to femme up). The Kemi's of the world were previously holding up Cass Review as the holy bible of treating gender dysphoria in children and young people, in the face of criticism regarding the significant above-mentioned flaws. Now, even the Randomised Control Trial, which a lot of trans people, their allies and medical professionals and academics who actually have some experience of working in this field had problems with anyway, is a step too far for them because ultimately it means an extremely small number of children and young people will actually receive puberty blockers. First they screamed that there wasn't enough evidence, so the government are attempting to get the evidence they demanded. So now they scream that this is "experimenting on children.'"
A begrudging "fair play" to Wes for actually standing his ground on this - the transphobes will always keep demanding you do more until there are no trans people anywhere or anyhow. Their demands are impossible to meet - so there is little point trying to appease them.