Reported Gemini UTM tagging could change how AI referrals appear in GA4

What changed

An attribution behaviour has been reported

A Reddit user reported that Gemini adds UTM parameters to links it sends users to, and Google’s John Mueller said he had seen the behaviour too. Search Engine Journal reported the observation. Neither the reported account nor Google documentation in the available material gives the exact parameter values or explains when the tagging applies.

That uncertainty is material. Tagged visits may be classified differently from untagged referrals or traffic that would otherwise appear in another analytics bucket, but the report does not establish a universal Gemini pattern. It also does not prove that every Gemini visit will leave the Direct category or that every UTM value apparently associated with AI traffic was added by Gemini.

Inspect actual values before defining a segment

Begin with first-party GA4 observations rather than a segment built around assumed parameter names. Review source and medium values, preserve examples of landing URLs where governance permits, and compare their dates with any visible movement between channel groups. Check whether the surrounding evidence supports a Gemini origin instead of relying only on a suggestive label.

A useful classification test should include positive, negative and unresolved examples. Positive examples meet the repeatable observed rule; negative examples are known Gemini-associated visits that lack it; unresolved examples contain similar tags without enough origin evidence. This comparison exposes whether the proposed segment is too narrow or likely to capture unrelated traffic.

If a reporting definition is adopted, document its exact observed values, effective date and exclusions. Retain an unclassified category when tags vary or are absent. This preserves the distinction between an emerging implementation behaviour and a stable measurement convention, and makes later revisions explainable.

Why it matters for advertisers

If Gemini applies campaign parameters, some AI referrals may move between GA4 channels and alter trends. A verified rule is needed before historical comparisons or Gemini-specific reporting can be trusted.