The same official pointed out that discontinuing treatment “will lead to the reactivation of the pituitary-gonadal axis; in that respect, the effects of [puberty blockers] are considered completely reversible”.
That's interesting - that is the technical definition of "reversible" I was thinking might justify the statement in another thread.
Yes, they haven't actually surgically removed anything, so the bits of the body can start working again, but you've disrupted the system.
Similarly, the standard contraceptive pill is fully reversible in that sense, but if you take it from age 20-35, you will significantly impact your chance of having a child. You won't switch back to age-20 fertility when you stop taking it.