Not able to send push notification from Azure Notification Hub after migrating to FCMv1 from FCM Legacy API

I am updating my production service to use FCMv1 APIs instead of FCM legacy as they have been terminated by ANH. After updating I am sending test notification from azure portal from Notification Hub -> Test Send. I am able to send normal messages like below to mobile apps and which gets delivered successfully.

{
    "message": {
        "notification": {
            "title": "message title",
            "body": "message body"
        }
    }
}

But when I am sending notification in below format I am getting error on the portal that Notification payload is invalid.

This is the actual notification I was sending earlier in legacy API and was working fine. I need to send in this format only as to support multiple languages, template is stored in mobile. I just need to pass title and body args in the notification.

{
    "notification": {
        "title_loc_key": "test_title",
        "title_loc_args": [
            "abcd title"
        ],
        "body_loc_key": "test_body",
        "body_loc_args": [
            "Test body text"
        ]
    }
}

Its also not working when notification is pushed from code as well. I can't find any document which states if there is a different format for sending args in FCMv1. Please help me fix this issue.