Two significant issues within GA4 and server-side GTM are causing duplicate events to occur.
Two digital analytics experts, Matteo Zambon and Giovani Ortolani Barbosa, have recently documented technical issues affecting Google Analytics 4 (GA4) and server-side Google Tag Manager (GTM) in recent weeks.
The first issue involves a discrepancy in the BigQuery event count estimates in GA4. Due to a daily limit of 1 million hits for BigQuery exports, organizations approaching this limit may encounter misleading estimates. This issue particularly affects e-commerce implementations and organizations with complex tracking requirements.
Zambon advises businesses to "always verify your event count directly in BigQuery" rather than trusting GA4's internal estimates. Organizations implementing custom event data import functionality face additional complexity from these bugs.
The second issue involves a communication breakdown between Google's gtag service and the service worker component, causing duplication of GA4 hits through server-side GTM containers. This disruption affects data accuracy and causes duplicate event tracking, impacting automated bidding algorithms, cost data import functionality, and data analysts using BigQuery for advanced analysis.
Current workaround options include blocking specific service worker files or removing iframe elements through JavaScript implementations. According to Barbosa's analysis, there is a bug in how gtag communicates with the service worker that prevents proper event acknowledgment.
Google's ongoing platform modernization efforts include the unification of the Tag Assistant tool and enhanced app measurement capabilities. The service worker implementation began earlier this year when Google tag started leveraging service workers to enhance data collection reliability. GA4 introduced Custom Event Data Import functionality on June 13, 2024, and Google unified Tag Assistant tools after user feedback for simplified debugging on January 2, 2025.
Google also announced BigQuery schema additions with batch_page_id and event ordering fields on July 16, 2024, to address some of these issues.
Technical teams managing GA4 implementations should immediately audit their current tracking setups, checking for duplicate events in server-side containers, comparing GA4 dashboard estimates against direct BigQuery queries, and implementing temporary workarounds while awaiting Google's official fixes.
Operational challenges are created for organizations managing data export costs and compliance with platform limitations due to this discrepancy. Community reports about duplicate events in server-side GTM implementations began surfacing in September 2024.
Zambon and Barbosa's findings highlight the importance of verifying event counts directly in BigQuery and staying vigilant when implementing new features in GA4 and server-side GTM. Organizations using these tools should prioritize regular audits and monitoring to ensure data accuracy and maintain a reliable understanding of their digital performance.
Read also:
- Ford Discontinues Popular Top-Seller in Staggering Shift, Labeled as a "Model T Event"
- 2025 Witnesses a 27% Surge in Worldwide Electric Vehicle Sales, Despite Opposition to Electrification Policies in the U.S.
- Summarized Report: Insights from the Realm of Transportation
- Recorded surge in electric vehicle registrations during the initial half of the year
