Creating a task through REST API

Hello Team,

I see the REST documentation mentions about creating a task for an existing contact. I was referring the below
https://developer.infusionsoft.com/docs/rest/#!/Task/createTaskUsingPOST_2

i have created the contact: id : 70 and when tried creating the task, it does not appear under the contact.
Request body:

{
  "completed": false,
  "completion_date": "2021-06-23T15:49:42.604-07:00",
  "contact": {
    "email": "test@test123.com",
    "first_name": "test1",
    "id": 70,
    "last_name": "test2"
  },
  "creation_date": "2021-06-23T15:49:42.604-07:00",
  "description": "testDesc",
  "due_date": "2021-06-23T15:49:42.604-07:00",
  "modification_date": "2021-06-23T15:49:42.604-07:00",
  "priority": 1,
  "remind_time": 0,
  "title": "Call",
  "type": "Other",
  "url": "testurl"
}

Response:

    "id": 14,
    "title": "Call",
    "description": "testDesc",
    "type": "Other",
    "priority": 1,
    "completed": false,
    "contact": {
        "id": 70,
        "email": null,
        "first_name": "CHIA-CHENG TU",
        "last_name": ""
    },
    "url": "https://api.infusionsoft.com/crm/rest/v1/tasks/14",
    "due_date": "2021-06-23T22:49:43.000Z",
    "creation_date": "2021-12-22T17:11:02.000Z",
    "modification_date": "2021-12-22T17:11:02.000Z",
    "completion_date": null,
    "remind_time": 0,
    "user_id": 28
}

my App id: https://bio997.infusionsoft.com/
Please advise. Thanks.