Microsoft is now using a Windows driver to prevent users from changing the configured Windows 10 and Windows 11 default browser through software or by manually modifying the Registry.
Long story short: That pop-up you get when you open Firefox (or whatever other browser) for the first time asking you if you want to make it your default browser won't work anymore. They're forcing you to go through their convoluted control panel where you have to change it like 20 times for each file extension.
Kinda wild how much they got destroyed for internet Explorer coming pre installed on Windows back in the day. Yet way more egregious shit just keeps happening to no response.