GA4 and Shopify Revenue Discrepancy

Finally on stackoverflow after having endless problems with matching GA4 analytics and Shopify revenue. First off -

I have integrated shopify and GA4 with GTM. I have created custom events and pulling the data as per. I also have installed Google & Youtube Application for Shopify and integrated with the exact GA4 account and it seemed the revenue is doubled up in GA4 compared to shopify in built analytic report which led me to think its the application which doubles up the revenue. So I disconnected the app from my current GA4 which turns comparatively low in revenue.

EXAMPLE

Revenue in numbers on 06 AUG 2023

Shopify: 4023 AED

GA4: 7200 AED

Revenue in numbers on 08 AUG 2023 (after disconnecting Google App - Shopify)

Shopify: 4073 AED

GA4: 483 AED

> How GA4 is integrated with shopify is

1. Implementing GTM tag on head on theme.liquid

   <script>
   window.dataLayer = window.dataLayer || [];
   </script>
   <script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
   new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
   j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
   'https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);
   })(window,document,'script','dataLayer','GTM-XXXXXXX');</script>
   

2. Implementing GTM tag on body on theme.liquid

3. Shopify settings -> additional script -> below code block

   <script>
   window.dataLayer = window.dataLayer || [];
   </script>
   <script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
   new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
   j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
   'https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);
   })(window,document,'script','dataLayer','GTM-XXXXXXX');</script>
   <script>
   products = [];
   {% for line_item in checkout.line_items %}
   products.push({
   'currency'            : '{{ shop.currency }}',
   'item_id'               : {{ line_item.product_id | json }},
   'item_sku'            : {{ line_item.sku | json }},
   'item_variant_id'  : {{ line_item.variant_id | json }},
   'item_name'        : {{ line_item.title | json }},
   'item_brand'        : {{shop.name | json}},
   'item_category'  : {{ line_item.product.type | json }},
   'price'                 :  {{ line_item.price | amount_without_currency | remove: "," | json }}/100.0,
   'quantity'            : {{ line_item.quantity | json }}
   });
   {% endfor %}
   transaction_data = {
   'transaction_id' : {{ checkout.order_number | json }},
   'affiliation' : {{ shop.name | json }},
   'value' : {{ checkout.total_price | amount_without_currency | remove: "," | remove: "." | json }}/100.0,
   'tax' : {{ checkout.tax_price | amount_without_currency | remove: "," | remove: "." | json }}/100.0,
   'shipping' : {{ checkout.shipping_price | amount_without_currency | remove: "," | remove: "." | json }}/100.0,
   'subtotal' : {{ checkout.subtotal_price | amount_without_currency | remove: "," | remove: "." | json }}/100.0,
   'coupon': '{{checkout.discounts[0].code}}',
   'discount': {{checkout.discounts_amount | amount_without_currency | remove: "," | remove: "." | json }}/100.0,
   'currency': '{{ shop.currency }}',
   'payment_type': '{{checkout.transactions.gateway}}',
   'items': products
   };
   user_data = {
   'full_name' : {{ checkout.shipping_address.name | json }},
   'first_name' : {{ checkout.shipping_address.first_name | json }},
   'last_name' : {{ checkout.shipping_address.last_name | json }},
   'address1' : {{ checkout.shipping_address.address1 | json }},
   'address2' : {{ checkout.shipping_address.address2 | json }},
   'street' : {{ checkout.shipping_address.street | json }},
   'city' : {{ checkout.shipping_address.city | json }},
   'province' : {{ checkout.shipping_address.province | json }},
   'zip' : {{ checkout.shipping_address.zip | json }},
   'country' : {{ checkout.shipping_address.country | json }},
   'phone' : {{ checkout.shipping_address.phone | json }},
   'email' : {{ checkout.email | json }}
   };
   </script>
   {% if first_time_accessed %}
   <script>
   dataLayer.push({
   'event' : 'purchase',
   'pageType' : 'nur_purchase',
   'ecommerce' : transaction_data,
   'user' : user_data
   }); 
   </script>
   {% endif %}
   

4. GA app is disconnected as below picture

More info can be provided, what can really cause the issue in lowering data revenue?

it is solved by uninstalling google app for shopify - prevents number conflicts and just keeping gtm script on head on theme.liquid and on custom script for ecommerce tracking on checkout -> additional scripts which was included above. of course there will be a few number is going to be different from shopify online store to ga4 since its not 100% accurate.