I have set up server side tagging for a client. I have done it several times for other clients.
On this client there has been a revenue discrepancy (about 20%) in GA4 compared to their webshop system (Dandomain - a danish provider) the last couple of months.
Have someone tried this before? It seems to be setup correctly, but there must be something i have overlooked.
FYI: The system, Dandomain, sends automatically events to GA4, so this is not setup in GTM.