It’s certainly possible that there are long term side effects from GLP-1 agonists, but we can only go with the data we have. The five year data (which definitely has limitations in terms of the kind of inferences we can draw from it) is suggesting around a 4x reduction in mortality at the 5 year mark in non-diabetics IIRC (https://pubmed.ncbi.nlm.nih.gov/39171569/).
The changes in behaviour are also really interesting. Even after cessation of the drug, it seems like many patients keep healthier eating patterns and while they do put on weight, they tend to settle on a lower weight than baseline before intervention.
So we should absolutely keep an eye on outcomes as time goes on, but so far the results are overwhelmingly positive. These drugs are saving lives and the new ones in the pipeline look significantly more effective. It’s an exciting time to be alive!