http://spywar2hncz3lkteymwfy7s6qxalsvw37gc4bywcf6v2b5hzjnwt5tad.onion/articles/bing.html
So since your search history is part of the "data we collect", the natural conclusion is that, your search queries are being used to profile you for advertising. And of course, this is confirmed in this section: "The ads that you see may be selected based on data we process about you, such as your interests and favorites, your location, your transactions, how you use our products, your search queries , or the content you view.