Why are my eCommerce analytics not matching with actual data?

Hello,

I launched a store, everything was fine then the 2nd day, all my analytics stopped working.

For yesterday for exemple, Tiktok ads sent approx. 300 visitors on my store but Shopify counts only 50.

My Shopify analytics shows 2 “add to cart” but I have 6 abandonned carts.

4 visitors buyed on my store, but Shopify analytics shows 2.

The Shopify support don’t have solution and keeps explaining to me that it’s normal.

It is very annoying.

Maybe a cookie problem ? I installed a GRPD app and uninstalled it, maybe the app edited the code of my store ?

Something in the settings ? I don’t know. Thank you