A lot of search extensions have been marketed over the year claiming to protect online privacy. Some of them are so similar in their advertising, wording, coding, and use of images, that there is no other explanation besides their developers deciding power. We looked at the code of the extensions to see if developers were paying attention to the privacy of the search or search results. We found no trace of any such code. The division rate of those that display their results on a site of their own and those that simply redirect us to Yahoo Search is about fifty-fifty.”]
Source: https://blog.malwarebytes.com/puppum/2018/08/can-search-extensions-keep-searches-private/