You Can Write a UTM Convention, but GA4 Never Reads Your Table
Because UTM values are free text: the table you wrote is read only by you, while GA4 reads the same string by its own rules. Google's published default channel group logic checks source against a list of 819 sites and checks medium against fixed regular expressions, so for one identical link your table says referral and GA4 counts it as Organic Search. The convention document is only half the job. The other half is pulling out the violations with a query on a schedule.
