The NHS advice is markedly different to New Zealand's Ministry of Health (emphasis added):
"Little is known about the long-term side effects of hormone or puberty blockers in children with gender dysphoria."
"Although the Gender Identity Development Service (GIDS) advises this is a physically reversible treatment if stopped, it is not known what the psychological effects may be."
Prior to June, 2020 the NHS described puberty blockers as "full reversible" but no longer does so.
"It's also not known whether hormone blockers affect the development of the teenage brain or children's bones."
Policy changes in detail
There have been several changes to the NHS advice regarding gender dysphoria and puberty blockers. In sum, the changes indicate a shift in emphasis away from hormonal treatments and towards psychotherapy.
A selection of these changes are highlighted in the following paragraphs. Green text indicates additions, r̶e̶d̶ ̶t̶e̶x̶t̶ indicates subtractions, and black text indicates the text has not changed. Some text has been bolded for emphasis.
"Treatment for children and young people"
"Y̶o̶u̶r̶ ̶c̶h̶i̶l̶d̶’̶s̶ ̶t̶r̶e̶a̶t̶m̶e̶n̶t̶ ̶s̶h̶o̶u̶l̶d̶ ̶b̶e̶ ̶a̶r̶r̶a̶n̶g̶e̶d̶ ̶w̶i̶t̶h̶ ̶a̶ ̶m̶u̶l̶t̶i̶-̶d̶i̶s̶c̶i̶p̶l̶i̶n̶a̶r̶y̶ ̶t̶e̶a̶m̶ ̶(̶M̶D̶T̶)̶.̶ ̶T̶h̶i̶s̶ ̶i̶s̶ ̶a̶ ̶g̶r̶o̶u̶p̶ ̶o̶f̶ ̶d̶i̶f̶f̶e̶r̶e̶n̶t̶ ̶h̶e̶a̶l̶t̶h̶c̶a̶r̶e̶ ̶p̶r̶o̶f̶e̶s̶s̶i̶o̶n̶a̶l̶s̶ ̶w̶o̶r̶k̶i̶n̶g̶ ̶t̶o̶g̶e̶t̶h̶e̶r̶,̶ ̶w̶h̶i̶c̶h̶ ̶m̶a̶y̶ ̶i̶n̶c̶l̶u̶d̶e̶ ̶s̶p̶e̶c̶i̶a̶l̶i̶s̶t̶s̶ ̶s̶u̶c̶h̶ ̶a̶s̶ ̶m̶e̶n̶t̶a̶l̶ ̶h̶e̶a̶l̶t̶h̶ ̶p̶r̶o̶f̶e̶s̶s̶i̶o̶n̶a̶l̶s̶ ̶a̶n̶d̶ ̶p̶a̶e̶d̶i̶a̶t̶r̶i̶c̶ ̶e̶n̶d̶o̶c̶r̶i̶n̶o̶l̶o̶g̶i̶s̶t̶s̶ ̶(̶s̶p̶e̶c̶i̶a̶l̶i̶s̶t̶s̶ ̶i̶n̶ ̶h̶o̶r̶m̶o̶n̶e̶ ̶c̶o̶n̶d̶i̶t̶i̶o̶n̶s̶ ̶i̶n̶ ̶c̶h̶i̶l̶d̶r̶e̶n̶)̶.̶"
Most treatments offered at this stage are psychological, rather than medical o̶r̶ ̶s̶u̶r̶g̶i̶c̶a̶l̶. This is because in many cases gender variant behaviour or feelings disappear as children t̶h̶e̶ ̶m̶a̶j̶o̶r̶i̶t̶y̶ ̶o̶f̶ ̶c̶h̶i̶l̶d̶r̶e̶n̶ ̶w̶i̶t̶h̶ ̶s̶u̶s̶p̶e̶c̶t̶e̶d̶ ̶g̶e̶n̶d̶e̶r̶ ̶d̶y̶s̶p̶h̶o̶r̶i̶a̶ ̶d̶o̶n̶'̶t̶ ̶h̶a̶v̶e̶ ̶t̶h̶e̶ ̶c̶o̶n̶d̶i̶t̶i̶o̶n̶ ̶o̶n̶c̶e̶ ̶t̶h̶e̶y̶ reach puberty
The reference to the multi-disciplinary-team and the endocrinologist have been deleted, along with an explainer that endocrinologists are "specialists in hormone conditions in children". The explainer could imply gender dysphoric children have a hormone condition in need of treatment, which is false.
The section casting doubt on a child's "suspected" gender dysphoria has also been deleted. The statement implied a distinction between 'true' transgender people who suffer from gender dysphoria, and children who do not go on to medical intervention and merely have "suspected" gender dysphoria. The updated text softens the distinction and implies that puberty can help resolve gender dysphoria.
"Hormone therapy in children and young people"
I̶f̶ ̶y̶o̶u̶r̶ ̶c̶h̶i̶l̶d̶ ̶h̶a̶s̶ ̶g̶e̶n̶d̶e̶r̶ ̶d̶y̶s̶p̶h̶o̶r̶i̶a̶ ̶a̶n̶d̶ ̶t̶h̶e̶y̶'̶v̶e̶ ̶r̶e̶a̶c̶h̶e̶d̶ ̶p̶u̶b̶e̶r̶t̶y̶,̶ ̶t̶h̶e̶y̶ ̶c̶o̶u̶l̶d̶ ̶b̶e̶ ̶t̶r̶e̶a̶t̶e̶d̶ ̶w̶i̶t̶h̶ ̶g̶o̶n̶a̶d̶o̶t̶r̶o̶p̶h̶i̶n̶-̶r̶e̶l̶e̶a̶s̶i̶n̶g̶ ̶h̶o̶r̶m̶o̶n̶e̶ ̶(̶G̶n̶R̶H̶)̶ ̶a̶n̶a̶l̶o̶g̶u̶e̶s̶.̶ ̶T̶h̶e̶s̶e̶ ̶a̶r̶e̶ ̶s̶y̶n̶t̶h̶e̶t̶i̶c̶ ̶(̶m̶a̶n̶-̶m̶a̶d̶e̶)̶ ̶h̶o̶r̶m̶o̶n̶e̶s̶ ̶t̶h̶a̶t̶ ̶s̶u̶p̶p̶r̶e̶s̶s̶ ̶t̶h̶e̶ ̶h̶o̶r̶m̶o̶n̶e̶s̶ ̶n̶a̶t̶u̶r̶a̶l̶l̶y̶ ̶p̶r̶o̶d̶u̶c̶e̶d̶ ̶b̶y̶ ̶t̶h̶e̶ ̶b̶o̶d̶y̶.̶Some young people with lasting signs of gender dysphoria who meet strict criteria may be referred to a hormone specialist (consultant endocrinologist) to see if they can take hormone blockers as they reach puberty. This is in addition to psychological support.
The updated text adds caveats and qualifies the criteria for referral to an endocrinologist. The text no longer creates an expectation that a gender dysphoric adolescent will be treated with blockers. The clarification is important because concerned parents naturally want their child's problems to be taken seriously and recieve the 'full' treatment.
Overall, the changes in the advice given on the NHS website signal a shift away from the biomedical treatment model of gender dysphoria in children towards a 'talk therapy' model. The shift is similar to the Finnish regime where blockers are only offered at centralised specialised research institutions. The model is in contrast to the liberalised approach in New Zealand where parents may be offered puberty blockers after a 10 minute consultation with a non-specialist at a local clinic.