Cannot remove MFA nor change method on my account

Question

I have been successfully using the MFA app for years, but I want to change the way it is set up—or completely remove and re-add it from scratch. However, I am unable to access the relevant settings. Every time I try to modify or remove MFA settings, I encounter different errors.

For example, when I try to access aka.ms/mfasetup, I receive the following error:

AADSTS90072: User account '<PII removed by Moderator>' from identity provider 'live.com' does not exist in tenant 'Microsoft Services' and cannot access the application '0000000c-0000-0000-c000-000000000000' (Microsoft App Access Panel) in that tenant. The account needs to be added as an external user in the tenant first. Sign out and sign in again with a different Azure Active Directory user account.

Additionally, when I attempt to remove MFA from My Microsoft Account > Security > Different ways to sign in, I get the following message:

"Microsoft Authenticator app cannot be removed. We are unable to remove the Microsoft Authenticator app at this time."

Despite these issues, I am still able to log in successfully, and I receive authentication approval requests on my mobile phone. However, I am unable to change or remove my current MFA methods, meaning I am forced to use it as it is.

I have access to all my security information, including my mobile phone number, recovery email, and all other security-related details for my account.

How can I resolve this issue and regain control over my MFA settings?