I watched something like this happen in a friend, but as an outside observer I saw a different explanation: The period when he got into shape involved a lot of changes for the better in his life, including becoming more outgoing, motivated, and disciplined (necessary prerequisites for weight loss in the pre-medication era). He also bought a new wardrobe and replaced his old worn out logo T-shirts and cargo shorts with clothes more appropriate for an adult. He also started paying attention to his grooming and hair style instead of looking like he just woke up.
For a while he tried to explain it all by his weight loss alone, but over time he realized it was an overall change in everything about the way he carried himself and presented himself to the world.
I won’t deny that there is some stigma around being overweight from some people, but I’ve also rarely seen a person change only their weight. Now that GLP-1s are everywhere I do know a few people who slimmed down rapidly without changing anything else and expected things like their dating life to completely change but have been disappointed that little has changed socially for them. They do feel a lot better though!