This is a complete 3-way scam, phishing, possibly fraud, and definitely false advertising.
There is no way that this is legal in any western nation.
The fact that this simple browser extension was sold for over 4 billion usd should be enough of a red flag that something is very shady about this by itself.
Its replacing affiliate links from influencers they sponsor without their (or the users) consent.
And actively working with shops to withhold coupon codes instead of 'giving you the best deals' as it claims too.
Frequently inserts affiliate links in without user consent by using browser notification 'get away' buttons and paypal checkout links as affiliate links.
And to top it all of frequently seems to be scamming the shops as well.