High discrepancies between Google Analytics (and other platforms) and Shopify

[notero88]

Since implemented, we´re experiencing a high discrepancy (about 60% off) between Shopify analytics and Google analytics 4 and other platforms such as Facebook ads, Google ads and TikTok Ads.
We´ve implemented GA4 through the standard Google analytics section in Shopify´s preferences. 
Facebook pixel has been setup through Meta´s Shopify app. 

About 70% of our traffic comes from cart permalinks that go directly to the checkout.Could this be affecting the tracking? 

Anyone else has experienced this? Any ideas of what could be happening? 
I really appreciate any help 🙂

[Kanish001]

Since 70% traffic comes from Cart permalinks, they might not have any history or ID of landing page views for the ads or analytics to link to and hence the discrepancy is there

And them landing on checkout fires checkout events but not landing page view or anything else and the ads aren't able to backtrack that click