Question about Seller Agent roles etc

I’m a member of the Amazon Associates program and I primarily promote deals (esp. promo codes).

I usually find codes on other websites (slickdeals, savewithcindy, etc. along with Amazon’s own deal listings)

I had posted on the Amazon Associates subreddit asking where sites like savewithcindy get their promo codes, because I don’t always see them in the official list of promo codes Amazon gives you in the associate promo page.

Someone mentioned savewithcindy is an “Amazon Seller Agent?” that is hired by sellers to distribute coupons/promo codes.

I’m curious, how do these seller agents work/what’s their incentive? Is there a way to easily find these agents so I can get easier access to promo codes and find ones my competitors in the “amazon deal” space don’t have?

Thank you!