Hello Chetana Kakade,
Thanks for your question.
Looks like the code is going to the old authenticator device.
To resolve this, if you have another admin they can help you re-require MFA for your account. See: https://learn.microsoft.com/en-us/entra/identity/authentication/howto-mfa-userdevicesettings#manage-user-authentication-options
However if there is no other admin, you need to contact global support here: https://support.microsoft.com/en-us/topic/global-customer-service-phone-numbers-c0389ade-5640-e588-8b0e-28de8afeb3f2
You can mark it 'Accept Answer' and 'Upvote' if this helped you
Regards,
Abiola