I am trying to deploy an ecommerce site on vercel that uses a square create payment api. It works perfectly on my local server, but when deployed, I get:

POST https://mySite.vercel.app/api 405 (Method Not Allowed)
error in cart async:  V {message: 'Request failed with status code 405', name: 'AxiosError', code: 'ERR_BAD_REQUEST', config: {…}, request: XMLHttpRequest, …}

this is my Api call:

  const checkout = async () => {
    try {
      const totalCost = cartItems.reduce((total, item) => total + item.product.price, 0);
      const items=stringifyCart()
      const response = await axios.post('/api',{cartItems: items, totalCost: totalCost},
        { headers: {'Content-Type': 'application/json'}});
      window.location.href = response.data.url;
    } catch (error) {
      console.error("error in cart async: ", error);
      alert('Something went wrong during checkout');
    }
  };

and my api/route.js (although i dont think the server even reaches this function):

const client = new Client({
  accessToken: process.env.SQUARE_ACCESS_TOKEN,
  environment: Environment.Production
});



export async function POST(req, res) {
  try {
    const { cartItems, totalCost, address } = await req.json();
    const response = await client.checkoutApi.createPaymentLink({
      idempotencyKey: new Date().getTime().toString(),
      quickPay: {
        name: cartItems,
        priceMoney: {
          amount: totalCost * 100,
          currency: 'USD'
        },
        locationId: process.env.SQUARE_LOCATION_ID
      },
      checkoutOptions: {
        askForShippingAddress: true,
        acceptedPaymentMethods: {
          applePay: true,
          googlePay: true,
          cashAppPay: true,
          afterpayClearpay: true
        }
      }
    });

    return NextResponse.json({ url: response.result.paymentLink.url }, { status: 200 });
  } catch (error) {
    console.error(error);
    return NextResponse.json({ error: error.message }, { status: 500 });
  }
};

I am currently on a vercel hobby account, but the same issue occcured on a paid account trial and when deployed to github pages. using npm run dev on my local, everything works as it should