incomplete flavor info from get server detail list on compute endpoint

Question

could anyone have any idea why does the flavor info returned from my api call of openstack list-servers return incomplete information?

Here is the documentation : https://developer.openstack.org/api-ref/compute/#list-servers-detailed

The api call have 200 http response code, so it's a valid call, only the flavor info is missing.

It's not about the version, because i use 2.53 for nova (compute endpoint), and the documentation said : "As of microversion 2.47 this contains a subset of the actual flavor information used to create the server instance, represented as a nested dictionary."

Here is my call :

Array
(
    [0] => Array
        (
    ........
            [flavor] => Array
                (
                    [id] => 8fbb7ade-4721-405c-931f-11fdefd5bffc
                    [links] => Array
                        (
                            [0] => Array
                                (
                                    [href] => http://xxx.xxx.xxx.xxx/flavors/8fbb7ade-4721-405c-931f-11fdefd5bffc
                                    [rel] => bookmark
                                )

                        )

                )
)

This is the expected result, taken from the docs above :

  "flavor": {
                "disk": 1,
                "ephemeral": 0,
                "extra_specs": {
                    "hw:cpu_model": "SandyBridge",
                    "hw:mem_page_size": "2048",
                    "hw:cpu_policy": "dedicated"
                },
                "original_name": "m1.tiny.specs",
                "ram": 512,
                "swap": 0,
                "vcpus": 1
            },