According to the docs the import statemenet should be as followed:
terraform import azuread_service_principal_delegated_permission_grant.example aaBBcDDeFG6h5JKLMN2PQrrssTTUUvWWxxxxxyyyzzz
However, terraform expects the following format:
terraform import azuread_service_principal_delegated_permission_grant.example /oauth2PermissionGrants/aaBBcDDeFG6h5JKLMN2PQrrssTTUUvWWxxxxxyyyzzz
Could you please update the documentation accordingly?