I had my surgery in July 2020. My total loss at my low point so far was 113 lbs (103 since surgery). I fluctuate up and down about 4 pounds.
I've read a lot of articles on regain and I've talked with both long term sleeve patients (10 years) and long term bypast (10-15 years), and short of a rare genetic or an unexpected medical issue, the issue of regain is all about the food. I only know a couple of people personally who have gained most/all their weight back (one sleeve, one bypass), and they went back to their old eating habits. As we all know, food is very powerful. It can be a force for good and for evil, and we have to go heavily to the good side, with just a little evil every now and then.
The people I have talked to who have been successful radically changed how they ate after surgery. They didn't outright exclude particular foods, but they concentrated on good choices and minimized processed foods and sugars. Basically, they stopped eating the standard American diet and made different choices.
I was determined to completely change my habits after surgery, which is one of the reasons I'm plant-based now, but that's not for everyone.
I think a little concern about regain can be used to help drive good choices, but it will always be a balancing act. Being too paranoid or obsessive about it isn't any fun and can be dangerous too.
I think once obese our bodies are primed to regain at the slightest opportunity. Our hormones are so out of whack, usually for many years prior to surgery, that I just don't think it takes much for our body to slip back into that mode if given the opportunity. I have no scientific evidence for those thoughts. It's just how I feel. So, I think it takes a pretty intentional plan to keep it going long-term.