There are several possibilities.

  1. Are you using other Shopify apps to set up GA4 measurements?

  2. Did you use other Shopify apps to set up GA4 measurements? We confirmed that there were sometimes other Shopify apps code on your theme.liquid after you uninstalled them. You need to delete these code.

    Demo_Store__Pafit____Edit___Dawn___Shopify.jpg

  3. Have you added GA4 measurement tags to your Checkout settings in Shopify?

    order status scripts.jpg

  4. Are you using Google Channels in your Shopify app?

    Shopify_and_Why_is_there_a_big_difference_between_the_sales_recorded_in_GA4_and_those_in_the_Shopify_store_.jpg

How to debug?

How many purchase events are there in the thank you page of GTM preview mode? If there is more than one purchase event, then other apps or something may be affected.

Therefore, we recommend that you delete the other Shopify apps.

GTM.jpg

We can check your settings

Please give us the permission.