I do think this is a complicated thing and it’s really individual - some people definitely have weight gain related to underlying medical/ hormonal imbalances , medications and often a lack of exercise too
others will regain the weight because they will go back to eating much as before when their appetite isn’t being artificially suppressed or they haven’t overcome the mental aspect of why they tend to overeat/over drink/ reach for snacks - whatever their individual weight gaining vice is.
in my case I lost quite a lot of weight ( not on WLI) and then I’m not sure why but I simply stopped weighing and started up again with the habits that caused the problem in the 1st place- not eating that much in the day but husband sized meals at night ( I like cooking) half a bottle of wine 3 times a week, cheese and ham croissant at breakfast etc - I’m not a snacker so to others my diet looked good - plenty of protein salad and veg, lots of fish, fruit , not much snacking - but on reflection lots of my evening meals would be 1100 cals on their own and apart from walking I did no excercise .
as I’m 63 and only 5ft 4 the reality is I need far less than what in theory I want - and it only takes the odd cake out once a week or a muffin or too many cappuccinos for it to tip over onto a small but constant gain
i myself have come off MJ after 6 weeks and am calorie counting , changed habits and have upped the exercise - will see how it goes - at the moment it’s still downwards in a similar pace to when I was using 2.5 MJ - but for me I don’t want/like suppression as I’ve got good willpower - I wanted to change habits and try new things and I didn’t like the fact ‘for me’ that I ended up eating an extremely limited bland diet to try and keep the heartburn and a bit of nausea and tummy ache at bay .
my own view and i know others won’t agree with me is that I feel you could have a go at maintaining your weight first without it for a few months if you reach a goal weight you are happy with, using your new changed habits and see how it goes - yes you may go up a few pounds, but then that’s little to lose by non medicated methods. I appreciate it’s got quite a few positive benefits generally but I’m not sure suppressing appetite for ever more is going to be that enjoyable a ride plus the moment an expensive ride!