Why is GA4 reporting lower revenue than UA?

[devatttd]

Hi. I'm using UA via the inbuilt settings. Enhanced ecommerce was turned off.

In December:

Shopify reports 49K revenue

UA reports 43K revenue.

About 2K disappeared in ReCharge subs and the other 3K might be something like slow scripts on order-status page, and I understand they will be a little different.

However......

GA4 reports only 18K revenue! Any ideas? https://woowoo.fun

What did I miss?

Notes:

The GA4 tag is added directly into the theme.liquid.

The "purchase" event is inserted to the order-status page via Shopify's [additional scripts] area with the following script:

<!-- GA4 checkout and datalayer scripts -->
<script async src="https://www.googletagmanager.com/gtag/js?id=G-Y0QGYZDMPZ"></script>
<script>
window.dataLayer = window.dataLayer || [];
function gtag(){dataLayer.push(arguments);}
gtag('js', new Date());
gtag('config', 'G-Y0QGYZDMPZ');
{% if first_time_accessed %}
gtag('event', 'purchase', {
"transaction_id": "{{order.order_number}}",
"value": {{total_price | times: 0.01}},
"currency": "{{ order.currency }}",
"tax": {{tax_price | times: 0.01}},
"shipping": {{shipping_price | times: 0.01}},
"items": [
{% for line_item in line_items %}{
"id": "{{line_item.product_id}}",
"name": "{{line_item.title}}",
"quantity": {{line_item.quantity}},
"price": {{line_item.line_price | times: 0.01}}
},{% endfor %}
]
});
{% endif %}
</script>
<!-- END GA4 checkout and datalayer scripts -->

[devatttd]

For anyone searching later that might find this, I moved the GA script into GTM, added GTM script to the checkout, and added the datalayer variables in GTM so they get sent to GA properly. All good now.

[Rabbica]

I will give it a try, thanks!