Hello @j-cCTV ,
When the server that stores the mandatory profile is unavailable, such as when the user is not connected to the corporate network, users with mandatory profiles can sign in with the locally cached copy of the mandatory profile, if one exists. Otherwise, the user will be signed in with a temporary profile.
User profiles become mandatory profiles when the administrator renames the NTuser.dat file (the registry hive) of each user's profile in the file system of the profile server from NTuser.dat to NTuser.man. The .man extension causes the user profile to be a read-only profile.
Use a lab or extra computer running a clean installation of Windows 10 to create a default user profile. Do not use a computer that is required for business (that is, a production computer). This process removes all domain accounts from the computer, including user profile folders.
Check out the below link to get to know further on the subject,
https://learn.microsoft.com/en-us/windows/client-management/mandatory-user-profile
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