The app automatically installs Bing Visual Search and includes code to decrypt cookies saved in other browsers, Rivera said, and it also brings a "free" geolocation web API to the system.
The developer discovered "many" nasty tricks Microsoft integrated in Bing Wallpapers, which include trying to change the browser's settings and set Edge as the default system browser. If the default browser isn't Edge, the app will open the default browser after some time asking to enable the previously installed Microsoft Bing Search for Chrome extension.
The good thing is you can disable most of their telemetry crap if you know what you are doing.
Should be opt in to begin with