Even if you uninstall edge, you can't make windows stop trying to open `microsoft-edge://` links with edge. The default-program-settings page lists it but it's a cruel joke because it doesn't let you actually pick anything except edge; you can't pick a custom program like you can for every other protocol. There are corresponding entries in the registry, and those you can edit to point at firefox... but they are simply ignored. It's quite frustrating.