Getting deprecated call header with simple order creation

In the meantime, you can avoid the deprecated warning by not setting any properties on the line_item object other than variant_id and price.

Here is an example of a valid request to create an order that sets a customer and sets a line item’s quantity to 1:

{
  "customer_id": CUSTOMER_ID_REDACTED,
  "line_items": [
    {
      "variant_id": VARIANT_ID_REDACTED,
      "quantity": 1
    }
  ]
}

This request will create an order with the specified customer and line item. It will not throw a deprecated warning.