What you recently ate can have a big impact. I only bought from reputable brands that had consistent dosages, but my diet could make two doses of the same gummy feel quite different night to night.
For me it was primarily how “heavy” the meal was. Eating 1lb of brisket with some bread would result in the edible taking longer to get into my bloodstream than something like a modest salad and some fruit.
I don’t know if that comes down to dosing, or if the body just reacts differently, but either way, it’s just rarely the experience I’m looking for.