curl --request PUT \
  --url https://{cluster}.voucherify.io/v1/loyalties/{campaignId}/rewards/{assignmentId} \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --header 'X-App-Id: <api-key>' \
  --header 'X-App-Token: <api-key>' \
  --data '{
  "parameters": {
    "loyalty": {
      "points": 3
    }
  }
}'

{
  "id": "rewa_Iw9VopmlLm0topBG17ZH1gp5",
  "reward_id": "rew_wg2pvCr5LDhCq4uVQZ9LhuZm",
  "related_object_id": "camp_fkZ28pe7DUAEmmabofkxHI8N",
  "related_object_type": "campaign",
  "parameters": {
    "loyalty": {
      "points": 3
    }
  },
  "created_at": "2022-11-28T18:54:19.747Z",
  "updated_at": "2022-11-28T19:27:40.604Z",
  "object": "reward_assignment"
}