I think it is about cards coming into the country. So mail it home wrapeed in Mylar (mylar does work to confound info doesnt it.)
So then the goverment can track mylar sales.
Maybe I’ll try putting some cash in a re-sealed potato chips bag, but I think somebody has already tried that.
Lead foil.
Only metalized Mylar. Regular Mylar is just another plastic, and transparent to radio waves. Think "Faraday cage".....same principle. Or you can just get an aluminum wallet. There are a lot of preventives out there.