The customer's story is as follows:

There is an employee who resigned. That employee was marked as inactive in BC and removed from Azure AD. After a few months, the employee was rehired. As a result, the employee was recreated in Azure AD and synchronized in Business Central. The issue is that the employee can no longer be linked to their existing account; instead, a new account is automatically created with a sequential number appended. So, what was userx becomes userx 1. Our customer does not want this; they want the user to be able to regain their old (userx) account.