https://arstechnica.com/gadgets/2017/09/siri-and-spotlight-will-now-use-google-not-bing-for-web-searches/

As of today, searching the Web with Siri or Spotlight on iOS and macOS devices will show you results from Google, not Microsoft’s Bing search engine. This ends a Bing integration that was introduced in iOS 7 back in 2013.

Google was already the default search engine in Safari in both iOS and macOS, and Apple is positioning this as a move for consistency, though there may be other reasons that have not been disclosed. In a statement released to TechCrunch, Apple said: