When an account is deactivated, the email address will be changed to "Deactivated-<Email address>". However, in this case, a user can create another account with the business using the same email address which was deactivated before. Due to which, when we try to deactivate the new account, it throws a "The guest could not be deactivated" error.
Example:
The below account has already been deactivated.
As the Guest can create another account with the same email address. In this case, the test user has created an account with the same email address . However, if we try to deactivate the new account, it will throw a "The guest could not be deactivated" error. 
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