It's a scam and a fraud. They replace affiliate ids with their own even if they don't provide any value.

They show the users of the extension worse coupon codes if the shops are partnered with them, a.k.a. paying them.

Full on enshittification. Fuck them.

The source is a well researched (as far as I can tell) video on youtube. The video id (since links are not allowed) is watch?v=vc4yL3YTwWk (just put it after the / in the youtube url)