I'm sorry to hear that you're experiencing this issue. I'm happy to help.
On the sign-in page where it asks you to enter the code from your authenticator app, click I cant use my app right now, then find the link that says Show more verification methods. This will give you the option to sign in using the available verification methods such as your phone or alternate email address.
If not, on the next page, click I dont have any of these. After clicking that, you will be prompted to complete the information needed to confirm that the account owner is making this sensitive change. Once your account is verified, you will be able to update your security information.
If you have recently made a sensitive security change, your account may be placed in a restricted state for 30 days.
This is done to protect you and alert you in case the security information was changed by someone without your permission. See: https://support.microsoft.com/account-billing/what-does-security-info-change-is-still-pending-mean-cbd0f64f-02d9-45d2-90c3-2375e5a72e52#:~:text=While%20we%20understand%20this%2030,phone%20number%20or%20email%20address