Your Multi-Factor Authentication
Multi-Factor Authentication (MFA) is a secondary method of authenticating access to your account, after your password. This adds another layer of protection to your account using something that only you have, such as your phone or another personal device.
When you upgrade your device, change your phone number, or even just perform a factory reset, this will break the connection with your device and the MFA. When this happens, when you attempt to sign in it will send the required notification to your old device (or old device configuration) and you will not receive it.
How do I fix this?
The easiest way to fix this is to reach out to service desk and have them remove the old device configuration to then set up your new one.
Service desk will need to verify your identity with security questions either over the phone or in person.