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Adding to above response, please make sure that you are signing in with an account that is part of the existing microsoft tenant and that you are using the email that was added to that tenant. The Authentication issues will also occur if you sign into Azure Portal using an account which is not added as an user to an Azure AD tenant.
The “Restricted Tenant” setting means that the tenant you’re trying to access is not allowed by your home tenant. To resolve this, ensure that your home tenant settings are updated to permit access to the other tenant.
If tenant restrictions were configured via corporate proxy infrastructure, administrators can access tenant restriction reports in the Azure portal under Azure Active Directory admin center > Azure Active Directory > Tenant Restrictions.
Follow the instructions in the documentation on how to set up a permitted tenant list using the Restrict-Access-To-Tenants HTTP header.
refer - https://learn.microsoft.com/en-us/entra/identity/enterprise-apps/tenant-restrictions.
Hope this answer helps! Please let us know if you have any further queries. I’m happy to assist you further.
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