Reference:
Default Endpoint Identity Groups Created for Endpoints
Cisco ISE creates the following five endpoint identity groups by default: Blacklist, GuestEndpoints, Profiled, RegisteredDevices, and Unknown. In addition, it creates two more identity groups, such as Cisco-IP-Phone and Workstation, which are associated to the Profiled (parent) identity group. A parent group is the default identity group that exists in the system.
https://www.cisco.com/c/en/us/td/docs/security/ise/2-4/admin_guide/b_ise_admin_guide_24/b_ise_admin_guide_24_new_chapter_010101.html#ID1678

Section: Architecture and Deployment

Explanation
https://www.cisco.com/c/en/us/td/docs/security/ise/2-1/admin_guide/b_ise_admin_guide_21/b_ise_admin_g