It appears that Mozilla has discovered an easy way to set Firefox browser as default in Windows OS.
In order to lower the risk of malware setting itself as a default app Windows doesn’t allow its users to set an application as the default for a particular task in the application itself, but instead, Windows will open a Settings menu where users will be able to manually choose their default browser. Along with that, Windows will warn you to rethink changing your default browser as Microsoft Edge provides the best experience and web protection.
No matter that, Mozilla has still found a way to set Firefox as a default browser with a simple click within the browser. Mozilla hasn’t provided more information on this matter except that this method relies on other Windows environment aspects in order to give people an experience close to what Windows provides to Edge when users choose Firefox as their default web browser.
Since the easy way includes bypassing malware prevention measures set by Windows, Microsoft responded to Mozilla saying that this method is not supported.