It can be a bit of a pickle when BigQuery can’t correctly match the source and medium to an event, can’t it? It appears that it defaults the source and medium as google/organic even if the gclid parameter is present in the link. Another issue I noticed is how it falls short in recognizing the source when it’s direct, resulting in cases where we don’t have these parameters for events at all.

Just to point out, however, these values are valid for the source and medium that acquired the user. And when I cross-compared the data in Universal Analytics (UA) and Google Analytics 4 (GA4), the session attribution seems to be correct. The crux of the issue might lie in the exporting process to BigQuery. Rest assured, I’ve reached out to support and am currently waiting for a response.