The Newtab adverts are not served by Google IIRC and they are only matched with you data locally in your browser, you get a lot of them from Mozilla and locally

The Newtab adverts are not served by Google IIRC and they are only matched with you data locally in your browser, you get a lot of them from Mozilla and locally on your machine they get targeted so you aren't tracked online (If my memory of the article on it is correct)