Tiggerito
Member
- Joined
- May 5, 2016
- Messages
- 41
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I'm not using UTM parameters, but do use a query param in my GMB links and I can see them to this day in GSC as separate pages.
Do your pages contain canonical tags?
Here's Google's announcement of the shift to reporting via canonicals. It indicates the reporting is based on Google's own choice of what is the canonical.

Consolidating your website traffic on canonical URLs
Official news on crawling and indexing sites for the Google index
GMB is its own thing in search results. The URLs it uses don't have to be in the index. Maybe their system does not do the canonicalisation for those entries as it may not have the data to work out the canonical.