It’s common to see higher transaction counts in the payment system than in GA4. The issue rarely comes from GA4 alone—most discrepancies arise in the transfer path between the gateway, GTM, and the GA4 API.
Typical causes include:
• Purchase events that never reach GA4 because the data layer is incomplete or misconfigured
• Identifier mismatches, especially in transaction_id
• Partial or failed event forwarding in GTM
• API requests that drop parameters or fail silently
What happens when the datasets diverge:
• Attribution becomes unreliable, as some sales exist only in the payment system
• GA4 underreports revenue, affecting ROI calculations and budget decisions
• Teams lose confidence in the numbers because the systems disagree
To fix it, ensure identity alignment:
• Validate the full event path from the gateway through GTM to GA4
• Confirm that all events include consistent identifiers
• Test on a limited segment, compare results in BigQuery, remove duplicates, and document the flow for your team
Data quality starts with consistent IDs and a verifiable transfer chain.
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