Amazon shouldn't allow anyone but 3M Authorized distributors to sell 3M respiratory protection

For FBA (fulfilled by Amazon) listings, that is indeed the case for listings with the correct brand.

Questionable sellers get around it by using another brand, for example

https://www.amazon.com/dp/B09HY48BK6

Note the * after 3M in the brand. Clicking on it will take you to a page that shows one other listing with this not-actually-3M brand name, for an 1860 -- another heavily counterfeited 3M surgical respirator.

Here's another: https://www.amazon.com//dp/B09GTKFQD9

"3M" is in the item title, but the brand is "Med Lab Supply"

Legitimate 3M retail branded products will show "Visit the 3M store" as the brand name -- for example https://www.amazon.com/dp/B095FJ36H2

3M products intended for "professional use only" will simply show "3M" as the brand, for example https://www.amazon.com/dp/B08J1THV9G, with that link taking you to https://www.amazon.com/s?k=3M, which is also redirected to from the short url https://www.amazon.com/3M

From that short URL, you can (on the left sidebar) select the "Respirators" department then "Amazon.com" as the seller. Direct link, sorted by ascending price.

Amazon carries much of 3M's commercial respiratory protection line, or lists inventory from their partners who fulfill on their behalf -- primarily Magid Glove, Global Industrial, and AGO Now.