A group of Microsoft Products and technologies used for sharing and managing content, knowledge, and applications.
You'd probably want to add an exception to your CA policies. Open the policy, go to the Users and Groups condition > Exclude > All guest and external users. Or vice versa, scope the policy to only include internal users. Refer to this article for more details: https://learn.microsoft.com/en-us/microsoft-365/security/office-365-security/identity-access-policies-guest-access?view=o365-worldwide