How do I unlink Microsoft Authenticator from my Amazon account?

Question

Some time ago, I enabled two-step verification on my Amazon account using the Microsoft Authenticator app. Since then, every time I try to change personal information or perform certain security actions, Amazon requires me to enter a one-time passcode (OTP) from that app.

Recently, I changed my phone. Unfortunately, Microsoft Authenticator did not properly back up all my accounts, and when I reinstalled it on my new device, my Amazon entry was missing. There was no way to restore it.

This has now become a serious problem because I am unable to complete certain actions on my Amazon account without entering an OTP, which I no longer have access to.

I contacted Amazon support, but they claim they cannot unlink my account from Microsoft Authenticator because the authentication is “owned by Microsoft.” This seems incorrect, since Amazon is the service that enforces two-step verification.

I believe one of these should be possible:

Restore the Amazon key to my Microsoft Authenticator app, or

Unlink Microsoft Authenticator from my Amazon account so I can set up a new 2-step verification method.

Has anyone experienced this before? Any suggestions on how to resolve this?

Thank you.