neowin[.]net/news/edgedeflector-1200-released-allows-setting-default-browser-for-news-and-interests/
There's lots of stuff in Win10 that will open a web browser to whatever page & content, and often the web browser used is Edge, regardless which browser you have set for Windows default. EdgeDeflector takes care of that, so every web page that Win10 opens will open in your choice of browser.