The discount coupons extension Honey was recently revealed to be a massive scam that has taken millions of rightful money from content creators. See: https://www.youtube.com/watch?v=8tDOeQqnrYQ
If Mozilla allows this extension to continue to be downloaded and used, Mozilla is basically allowing the scam to continue happening by inaction.
This is the original video which that video is talking about:
https://www.youtube.com/watch?v=vc4yL3YTwWk
(Exposing the Honey Influencer Scam)
Basically they are doing Cookie stuffing:
But in this case it’s a gray area - since users can indeed get a discount in some cases.
The problem is all the other cases - if there is no discount and Honey will still “stuff their cookie” for your purchase - this could be considered an affiliate fraud.
This is a very popular technique these days as big stores are often letting it slide (maybe because it doesn’t hurt the user directly):
UPDATE:
It looks like this guy already investigated honey in the past but for a privacy related issues and at that time Firefox removed the “Recommended” badge: