A software developer made a Chrome and Firefox extension called Knockoff that automatically hides, grays out, or filters products from sketchy brands on Amazon, which highlights just how many shady brands are on the platform and how commonly they show up on searches for basic items.
Actually; even using your own Cambridge dictionary definition and examples you linked, it fully shows that I’m correct. Like, just look at the example you provided that talks about a cheap knock off of lord of the rings, for example.
If you aren’t able to understand that, then I guess you’re just a bit too dumb to comprehend.