Google Gemini Apparently Dropped UTM Tags From Cited URLs

By Tom Whitfield

Around September 28, multiple observers saw the URLs Google Gemini cites in AI responses stop carrying utm_source=gemini, a UTM parameter (a tracking tag appended to the link) first seen in early September. The drop appears abrupt: a three-week tracking chart shows tagged links increasing before they disappeared overnight. The observations point to an attribution change, not a documented Google policy update.

Natzir, who has followed Gemini’s link behavior, shared the chart on X. In an October 27, 2026 post, he wrote: “Not just me. @Xyborg sees the same drop around Sep 28 in Gemini's answers! The cited URLs stopped carrying utm_source.” His observation aligns with a separate report from @Xyborg.

Google’s John Mueller also commented on Reddit: “I saw the UTM parameters on Gemini links a month or so ago.” That supports the timing of the change, but it does not establish why Google removed the tags or whether the removal is permanent. Neither post constitutes a formal Google announcement.

The UTM parameter gives an analytics system an explicit source label for a visit. Its disappearance affects measurement of Gemini referrals. The observations do not show that Gemini stopped citing pages, reduced clicks or changed rankings, so the event should not be treated as a visibility signal.

The distinction between a UTM parameter and a referrer matters here. A referrer identifies the sending site or page. Natzir said Google still passes referrer data (the field identifying the sending site or page) from Gemini’s desktop web version, and visits with a gemini.google.com referrer stayed flat throughout the period he monitored.

That means the evidence does not show a desktop traffic decline tied to the tag change. It shows a change in an attribution mechanism: cited URLs no longer carry the explicit Gemini UTM value, while desktop referrals can still be recognized through the referrer. “Flat” referral volume should not be read as evidence that tag removal had no reporting consequences.

iOS app behavior remains different. In an October 28, 2026 test comparing the iOS app with the web app, Natzir reported that the app opens cited links in its own WebView (an embedded browser) and sends no referrer. GA4 (Google Analytics 4) then records those visits as Direct.

He said the only remaining trace was the Gemini iOS user agent in server logs, which he found and @rustybrick also covered. That creates a measurement gap between platforms: an analyst looking only at GA4’s default source and referrer fields could treat app-originated visits as direct, even though the server request identifies Gemini.

What does this change for site owners?

For publishers and other sites receiving Gemini citations, the immediate task is to separate web from app behavior in reporting. Desktop data can retain gemini.google.com as a referrer even without utm_source=gemini; iOS visits may require checking server logs for the Gemini user agent rather than relying on GA4’s Direct classification.

No one has reported a vertical-specific pattern, so the evidence does not justify treating one content category differently from another. The measured issue is acquisition attribution across sites, not a publishing category.

The removal can alter campaign-level reporting even if desktop referral volume does not move. Teams should distinguish the loss of an explicit URL label from the loss of visits before interpreting GA4 totals.

No Google policy statement has confirmed the reason for the September reversal or whether it is permanent. With no explanation from Google, the next signals to watch are any renewed utm_source=gemini tagging, further web-versus-iOS tests, and whether gemini.google.com referrals remain stable.