Zoho Billing Retrieve API issue

I've been using the api below

and suddenly I got error message as html since today.

    const customer_res = await axios.get(
      `https://www.zohoapis.com/billing/v1/customers?display_name=${account_name}`,
      {
        headers: {
          Authorization: `Zoho-oauthtoken ${accessToken}`,
          "X-com-zoho-subscriptions-organizationid": biiling_id,
        },
      }
    );