Salesforce MFA will not be supported when multiple users shares/uses the same login credentials.
Sharing user credentials is not a good practice. Salesforce MFA is not possible for this use case.
Note:
MFA Registration can be disconnected so that the user can be prompted again to register.
Salesforce prohibits sharing user credentials with multiple users. Before you can satisfy the MFA requirement, you need to resolve any shared accounts or credentials that are in use. This practice is incompatible with MFA because each user must register and connect a unique verification method to their Salesforce account before they can log in. If multiple users are sharing a single account, only one person will be able to log in to that account after MFA is enabled.
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