Since the federated user does not have any domain, it is expected that the domain field will be greyed out.
A possible solution would be, add a condition to check if the user is federated, if yes use the domain from the scoped project instead of the user domain.
The domain is populated using the user's domain: https:/ /github. com/openstack/ horizon/ blob/master/ openstack_ dashboard/ api/keystone. py#L232
Since the federated user does not have any domain, it is expected that the domain field will be greyed out.
A possible solution would be, add a condition to check if the user is federated, if yes use the domain from the scoped project instead of the user domain.