So after reading everyone's posts on this thread so far no one understands how these apps and sites work.
It's simple cash back, there are tons of sites and apps that do this. And if you notice almost all the stores you earn from are the same and have similar returns. Most of the cash back sites pay out in gift cards or paypal, a few do crypto which I think is great. As for "a few sats" between the my personal uses of cashback sites I've earned about 2.5k in the past 3 years not doing anything out of the normal.
So do you think these sites are paying you money for free then what is the benefit for that site? They are actually collecting the user data to target advertisements based on what they are buying more often, sooner or later you will see that kind of ads that you like to buy will popup while surfing the internet or while scrolling newsfeed, social media.
So they are targetting you and tempting you to buy a product even if you are actually no need that, you will actually spend more money but you consider you saved money by spending there.