Appetite suppression fading then disappearing on the same dose while weight stays flat is not tolerance, it is how all these GLP drugs behave. On any fixed dose the body has a set weight it wants to hold. Above that weight you feel appetite suppression, once you hit it the suppression ends. Regain weight on the same dose and suppression returns until you are back at the set point. To drop further you raise the dose, which lowers the target weight and brings suppression back until you reach it. True tolerance has never shown up in the thousands of people tracked over four plus years in the sema and tirz trials. If tolerance were happening weight would trend back toward starting levels. Evidence is building that stopping and restarting later can lower how well it works again, possibly from the body making antibodies to the drug. The same thing shows up with other peptide drugs.
I would push back on that, not every batch is made or stored the same way.