Open an Explore report a few weeks into a campaign and it’s not unusual to find the same source listed three times: Facebook, facebook, Facebok. Three people built three links on three different days, and GA4 has no reason to think they’re related: a UTM parameter is just a string, matched exactly, with no idea that two of those strings were supposed to mean the same platform.
The Default Channel Group papers over it at a glance: all three still roll up into “Paid Social” in the summary view. Drop into the raw Session source / medium dimension, in Explore, BigQuery, or a Looker Studio pull, and the split is right there: three rows, three session counts, three conversion rates, none of them the number anyone’s actually trying to read off a dashboard.
Nothing about this looks broken. No errors, no gaps, nothing a QA pass would catch, because every individual hit did exactly what it was told to do. What’s missing sits upstream of GA4 entirely: a shared, agreed vocabulary for what counts as “Facebook” that existed before the links went out, not one reconstructed afterward from three rows that don’t obviously belong together.