If it was a printed coupon and photocopied it would be obviously illegal, I’m not sure how the digital equivalent would not be illegal. If such a coupon was publicly available then it would be like if honey went and fetched you a new coupon instead of copying an existing one.

Even if the user says they have the right it doesn’t mean they do, and at what point does it become handling stolen goods. Consider a scrap dealer accepting a clearly stolen catalytic converter, would that still be illegal if the scrap dealer did not pay for it? How ‘clearly stolen’ would it have to be to be illegal. What is a reasonable amount of verification?

There are three businesses involved. A 3rd party (eg YouTube reviewer) has their affiliate code stripped from the page, and as a result is losing out on income. That may be illegal. And the affiliate doesn’t have a business relationship with honey. They didn’t sign anything away with them.

Also honey was (until recently) marketing themselves as “we find you the best coupon code”. That was & is false advertising, since they were clearly hiding coupon codes they knew about when companies paid them to do so.