It's essentially used by Google to see which search result you clicked on from the original query. Twitter does similar thing with t.co. It never used to happen

It's essentially used by Google to see which search result you clicked on from the original query. Twitter does similar thing with t.co. It never used to happen on a non-logged in Google account, but now it does. It's been like that for at least half a year. The Greasemonkey script is a great work-around, especially if you value your privacy. Or alternatively why not try DuckDuckGo?