To connect refund data beyond the 3-day window using GA4’s Measurement protocol, you’d need to keep a consistent identifier (like transaction ID) between the purchase and the refund. This will let you link the two events even after the 3-day window. If you want to understand acquisition channels leading to most refunds, a programmatic solution in GA4 might not be enough. Using a more advanced data analytics tool like BigQuery or LookerStudio to analyze refund data in relation to other metrics might be a more effective option. It’s true that GA4 doesn’t preserve the full transaction attribution in the report, so a detailed data analysis using these other tools may provide more clarity.