If that is true, and it makes mechanistic sense if I think about opiod withdrawals for example, then it is a problem regardless. If you have a stronger hunger impulse then before AND a lower body weight and thus TDEE, I can imagine that it would be pretty tough mentally to maintain your weight, even if you count your calories.
I foresee the overwhelming majority of people on these drugs regaining everything (and maybe even going beyond their original weight), because, just like traditional dieting, they don't actually change their lifestyle. They're just giving their system a shock, which when it goes back into fat storing mode will overcompensate due to the shock of the loss.
The nihilist in me doesn't believe that many people are truly capable of massive lifestyle change. Once you've lived a certain way for 20 or 30 years, any change beyond that is just a fleeting thing. Yo-yo weight loss and gain just proves that. It only becomes a real lifestyle change after many years.
If there are sweets in the house, I may eat more than I would like, but I don't really have those voices, and after being married to my wife for 40 years, I can't pretend to even understand what her thoughts are about food. I can get a brownie from the kitchen, eat it and forget about them until I come back into the kitchen again. I suspect you also don't have those voices.
(For reference, I've never been particularly overweight, but twice in my life my weight crept up, and I managed to lose and keep off for years 10-25 pounds through diet changes alone; yes, my weight did eventually creep up, but I think the number of years before that happened would qualify medically as a successful weight loss)
To get back to this discussion, my son-in-law has lost 50 pounds since he started taking the GLP-1 drug, but he has also changed his diet and he exercises regularly. He was trying to do those things with mixed success in terms of weight loss before he started taking the drug, so I would say he would probably stand a higher chance of keeping the weight off if he were to stop the drug, but his doctor talks about him always being on a low maintenance dose.
If you can master the skill of dietary control, and go a month or two with really spartan fasting routine between celebration periods, life becomes a lot less stressful. I always enjoy watching Paddy Pimblett (UFC fighter well known for radical weight transformations:https://www.bbc.com/sport/mixed-martial-arts/62135535) bounce between weights, but always get in shape before a fight. It's a skill that only gets easier with practice.
If purely used as an appetite suppressant, then of course people will put the weight back on as soon as they regain their appetite.
People get lulled into a false sense of security that their diet is fine because they're losing weight! But it isn't.
However the jabs work well if you use the time to "retrain" your appetite, diet, and tastebuds. Then you keep the weight off because you no longer crave processed, high calorie, or junk foods.
I think the problem is in the marketing of these medications. They're not slimming jabs, they're appetite suppressors. If you never fix the appetite you will need to go back to suppressing it!