If it is “added ingredients”, couldn’t some PB without be sourced? Mine at home says “peanuts (90%), sugar, fractionated palm oil, salt”. I know that some can be purchased which are pure peanut, with no additives.

it's not like aflatoxin would show up in "added ingredients". It's not meant to be there. (If you haven't read the text, the author's thesis is that it that a few fungi infected peanuts make it through quality control.)