Sending custom response in netlify-forms submission

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,
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using this solution, it returns me with an 403 forbidden error , any luck you know why this is happening?

this is the request config i am using, is there anything wrong here?

 const response = await axios.post(
        "/.netlify/functions/submission-created",
        {
          "form-name": "contact",
          countrycode: values.countrycode,
          mobilenumber: values.mobilenumber,
        },
        {
          headers: {
            "Content-Type": "application/x-www-form-urlencoded",
            Accept: "application/json",
          },
        },
      );