Azure AD Guest Accounts have a habit of becoming stale or obsolete as time progresses. Guest accounts created to share documents or to be a member of a long-forgotten team or group remain in Azure AD until someone comes to clean them up. This article explains how we refreshed a popular script to use cmdlets from the Microsoft Graph PowerShell SDK to report guest accounts with different degrees of staleness.
https://office365itpros.com/2023/01/18/old-azure-ad-guest-accounts/
