I imagine the effectiveness of GAC as a treatment for dysphoria distress is also very dependent on how 'passing' the individual is afterwards. Some biological men can pass pretty well, others not so much, and there seems to be little the treatment itself is a factor there.
"GAC" I think is an umbrella that can just be hormones, but can graduate into GRS...if I read it right, the studies above are mostly about the results of surgery, and while there's facial feminization and boob jobs, bottom surgery isn't as much about passing
if surgery has a pattern of immediately feeling fulfillment followed by a rising risk of death after 10+ years, my uninformed guess would be that a major aspect of it is social
no trans person is an island...after receiving surgery, you become a spokesperson and advocate for other trans people, everyone on discord and reddit who supported you on this journey becomes even more supportive, celebratory and jealous...you become someone others ask for advice, you're the subject of studies and interviews, you're the belle of the ball
it is your responsibility to tell everyone else it's worth it, and if you quietly have doubts, you are led to feel that those misgivings are unique to you alone, because everyone in the past also said it was super worth it and led to immediate fulfillment
so you keep your chin up for a few years, but after a while the surgeries and hormone injections wear you down physically and mentally, and a decade down the line any sense of newness or specialness is long gone, and you've settled into the drudgery of daily life with the choices you've made
but that's just a guess, and I hope that's not too heartless or cruel an assessment of the situation, just based on how things feel having been an internet denizen for a long time