Hello, thank you for reaching out to Microsoft Q&A.
Did you back up your authenticator credentials to a recovery account before you switched to a new mobile device?
If you previously added a recovery account, select "Start Recovery" in the Authenticator app and enter your recovery account credentials before signing in.
Enter the recovery email address and Password.
1• You'll be prompted to verify your identity through the Authenticator app.
2• Select "I can't use the Authenticator app right now" or choose "Show more verification methods."
3• You can then use alternative verification methods, such as your phone number or email address, to confirm your identity.
Sometimes you may be prompted to reset your password. After the reset, select "Start Recovery" again and add your account to the Authenticator app.
let me know if you still need more help.