We do know these drugs have high side effects, which is why the usage is restricted when used for what it is licenced for.
Using them to put a child in stasis is not one of them. Using them for years is against all usage guidelines.
We know that the reasoning is because adult men wanted boys who might grow up to want to be women, to not develop properly, in order to pass more easily. The very reason was to stop development.
We know that the two trial cases were girls though, and they did this because their parents didn't want butch lesbian daughters.
None of the original reasoning makes sense when they trialled it on girls not boys.
We know that the Dutch 'trials' were being done AFTER WPATH guidelines were stating it was an OK medical pathway. The evidence as to how they made this decision is difficult to find as they have wiped the old SOC documents which changed their 'don't do it to kids' guidance to 'do it to kids' guidance.
They didn't lose their long term studies, they didn't ever plan to DO long term studies.
When the GIDS wanted to trial it, they had to go to at least two ethics boards, and they were finally given permission to trial it aged 12 and above, and they then ignored the age restriction AND DELIBERATELY only asked for approval to get patient feedback until they got to 16.
This has specifically always been designed to avoid collecting evidence because from the beginning, they knew about the harms. They have been doing this for at least a generation already.
This whole thing is an experiment they did on kids and the follow up has been specifically designed out. This is not a 'my dog ate my follow up studies' situation.