serializer adds unnnecesary fields in Javascript

I need to generate a very clean structure of an JS Array from Django Queryset. For this I'm using a serializer.

However, they final array has extra field that may be causing problems with Google Analytics requested format.

Google Analytics resquested format:

Notice the structure of the products Array

<script>
// Send transaction data with a pageview if available
// when the page loads. Otherwise, use an event when the transaction
// data becomes available.
dataLayer.push({
  'ecommerce': {
    'purchase': {
      'actionField': {
        'id': 'T12345',                         // Transaction ID. Required for purchases and refunds.
        'affiliation': 'Online Store',
        'revenue': '35.43',                     // Total transaction value (incl. tax and shipping)
        'tax':'4.90',
        'shipping': '5.99',
        'coupon': 'SUMMER_SALE'
      },
      'products': [{                            // List of productFieldObjects.
        'name': 'Triblend Android T-Shirt',     // Name or ID is required.
        'id': '12345',
        'price': '15.25',
        'brand': 'Google',
        'category': 'Apparel',
        'variant': 'Gray',
        'quantity': 1,
        'coupon': ''                            // Optional fields may be omitted or set to empty string.
       },
       {
        'name': 'Donut Friday Scented T-Shirt',
        'id': '67890',
        'price': '33.75',
        'brand': 'Google',
        'category': 'Apparel',
        'variant': 'Black',
        'quantity': 1
       }]
    }
  }
});
</script>

dataLayer product array produced by serializer:

View that contains the serializer:

def thanks_deposit_payment(request):
    order_number = Order.objects.latest('id').id

    total = Order.objects.latest('id').total

    costo_despacho = Order.objects.latest('id').shipping_cost

    order_items = OrderItem.objects.filter(order=Order.objects.latest('id'))


    order_items = serialize('json', order_items, fields=['id', 'sku', 'name', 'price', 'size', 'quantity'])


    response = render(request, 'thanks_deposit_payment.html', dict(order_number=order_number, total=total,
                                                                   order_items=order_items, costo_despacho=costo_despacho))
    return response

dataLayer in template:

This is the line that produces the Products Array that is what needs to be changed:

 products: JSON.parse('{{ order_items | safe }}')

Complete JS code in template:

{% block data_layer %}

<script>
    window.dataLayer = window.dataLayer || [];
    window.dataLayer.push({
        event: 'eec.purchase',
        ecommerce: {
            currencyCode: 'PEN',
            purchase: {
                actionField: {
                    id: {{ order_number }},
                    affiliation: 'Stickers Gallito E-Commerce',
                    revenue: {{ total }},
                    shipping: {{ costo_despacho }},
                    coupon: ''
                },
                products: JSON.parse('{{ order_items | safe }}')
            },

        }
    });
</script>

{% endblock %}

How can I match the expected format by Google?