Publishers are shilling amazon's prime day because they're all amazon affiliates wanting to earn their commission. Similarly, all those "price comparison" and coupon sites are injecting affiliate codes and just redirecting you to the merchant.
I don't see how Brave did something egregious injecting affiliate codes to earn commission from certain vendors, if one of their users signed up for a service. Keep in mind the dominant, alternative browser (Chrome), built by an advertising company, is privacy hostile and trying to use new tracking technology (FLOC) as they phase out cookies. Firefox is kept alive largely by $ paid by Google and seems to be getting worse with each release also. I'd rather see a competitive browser that doesn't have to take $$ from Google to stay alive.