Vacuum pull on peptide vials: real quality marker or forum lore?

For what it's worth, i keep seeing people say a lyophilized vial should make a little whoosh when you open it, and if it doesn’t, the batch is junk. I’m skeptical. I’ve had four vials over the last couple months—two had a noticeable inward pull on the stopper, one was neutral, one arrived with the rubber slightly domed. All were stored the same way in my fridge door, away from light. I can’t tell if that’s a manufacturing/pressure thing or an actual stability clue. Has anyone found a plain-language source—pharmacy tech explainer, USP chapter, manufacturer FAQ—that says vacuum is required? And does it even matter once the powder is in my hands? Not looking for dosing advice, just trying to separate packaging quirks from real red flags.