Oh yes, OP said they happen to have bags with aluminium, so there is no confusion this time. We can assume the OP is talking about ESD shielding bags, thanks to that clarification.
But, if we don't correct OP's terminology, the risk of OP continuing to talk about "mylar bags" when they actually mean "ESD shielding bags" is high, and this has at least two practical consequences:
* Confusion in further communications,
* Someone (OP themselves, or someone else) getting the wrong kind of bags.
Also, I wouldn't use Mylar food storage bags for storage of ESD sensitive part, even if they have aluminium layer. Proper ESD shielding bags are not expensive, they also have printing which tells you they are static shielding / moisture barrier bags. And you usually accumulate those bags anyway when ordering from component distributors, and they can be reused for many many times.
Indeed if you just google "Mylar bag" you mostly get image results of foil bags but that being said, most of the results actually do not contain the string "Mylar bag", Google is just finding products described as "Mylar foil bag", "Foil bag", "Mylar barrier bag" etc. These added words make a big difference!
I don't understand your motivation here. I'm sure OP posted the question exactly to gain understanding about the types of bags and the terminology. It's not that we are correcting the wrong assumptions and terminology out of malice, quite the opposite.