iCloud has stopped signing in on the Firefox browser for Windows. I contacted Apple Support and they told me that this is an issue on Firefox's part, and told me to try signing in the next morning and they guarantee it'll work. It did not. In fact, it has been over a week, and it still does not work. When I enter my Apple ID and Password, the website gives me an error "Failed to verify your identity. Try again." The website does NOT send me to the 2fa screen, yet it still sends a 2fa code to my iPad nonetheless. As Apple has said this is an issue on Firefox's part, I am posting this here. Attached is a screenshot of the error.