curl --request PUT \
  --url https://api.loyalty.dog/v2/loyalty/programs/{programId}/customFields \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
[
  {
    "name": "<string>",
    "type": "text",
    "displayName": "<string>",
    "defaultValue": "<string>",
    "points": 123,
    "options": "<string>",
    "required": true
  }
]
'

{
  "detail": [
    {
      "loc": [
        "<string>"
      ],
      "msg": "<string>",
      "type": "<string>",
      "input": "<unknown>",
      "ctx": {}
    }
  ]
}