How is buying on ebay different than buying from amazon?
You think manufacturing PPE is more complicated than manufacturing iPhones?
I'll take the rhetorical. The good majority of the enterprise CPU's come from either TSMC or the Intel fabs at Portland or Phoenix. The defect rate is the same, yes, but the quality control is far different. Even if 3M manufacturers stuff in the same factory that TeamHealth does (which they do in Shanghai), the people during the day shift for 3M do a non-****ty job of quality control throwing away the ones that suck. The night group which does not have the same standards will gleefully sell things that wouldn't pass the day shift quality control check.
So 90% of the time, it'll be just fine. 10% of the time, what would have been thrown out by the manufacturer in the day time are sold under the third shift brand, and the third shift brand does not have the same standards for quality control for the stuff they have at night. So electronics, I buy from wherever I know the fab source irrespective of brand. My favorite keyboard for work happens to be a Taiwanese brand that manufactures Das Keyboard in the day and Ducky at night (it is now to the point though that Ducky is a brand of its own). Ducky keyboards are really good and are quite artistic, so I have those in the prestige office, while I keep a Das in any work area that needs standardization. But masks, I wouldn't care either even if defective because it's just the odds anyway. Meds and anything I ingest like food, I hate the idea of eating anything from China, so I won't eat catfish (swai) or other things shipped to China for butchering and then shipped back here as 10% is a bit much for my taste.
It's up to you what to source, but if you happen to know the OEM of the part (like the mask) being the same factory as what the brand material comes from, then you make a decision. There are certain OEMS though that are trusted, I definitely trust Hon Hai (Foxconn) as they manufacture for HPE and Apple. I trust Norinco because their guns are good enough for the Chinese military. You just trade price for higher risk, but if you do the research, it is a good value proposition in many cases.