Personal key not working
A personal key is a 16-character secret code we used to generate for users when creating an account. Currently we are moving away from using personal keys and instead requesting the users to configure one or more second factor authentication mechanisms such as backup codes, authentication apps, security keys, or phones. The personal key used to be the only way to sign in if you lost access to the device you use for two-factor authentication. You could only use your personal key once. Once used, you would immediately receive a new personal key and your old key would no longer work. If you still have a personal key option upon login it means you did not use your last generated key yet.
If you still have a personal key option upon login it means you did not use your last generate key yet. Being told your personal key is invalid means you have either typed it incorrectly or you have already used it to sign in and it is no longer valid. If you have already used your personal key to sign in, you were given a new one that must be used to sign in.
Once you use the last generated personal key you will be asked to configure a new authentication mechanism as a new personal key will no longer be generated.