I have a -20% discrepancy in reported sales between Shopify and GA4. Any suggestions as how to trouble shoot.
I had been using GA4 and UA in parallel for over a year in anticipation of the retirement of UA. GA4 was implemented using Google Tag Manager. Sales and ATC data tracked. When Shopify FINALLY introduced their integration in March I retired the GTM work-around and deleted custom tags (ATC, etc.). Reported GA4 revenues ane 20% below those reported in Shopify Analytics. Any suggestions as to root cause and trouble shooting?