Global users experienced a sudden 22% to 57% drop in Google Analytics 4 traffic from ChatGPT starting October 9, 2026. Analytics platforms and engineers confirmed the dip stemmed from OpenAI’s GPT-6 rollout, which briefly stripped UTM tracking parameters from external links before a fix restored them on October 15.
GPT-6 Rollout Alters Interface and Drops Tracking Parameters
OpenAI introduced its latest generation of AI models alongside a brand-new Intelligent UI feature in ChatGPT that fundamentally changes how the assistant answers queries. Rather than relying solely on text, the system now blends diagrams, interactive charts, forms, and tappable buttons directly into conversational responses.
Since octobre 9th I also see a sharp drop in Chat GPT human traffic, and also a drop of Chatgpt-user robot traffic. OAi Search bot traffic has increased in the same time (sinc october 7th be precise). Am going to investigate the utm parameter.
The global rollout brought GPT-6 to ChatGPT Plus, Pro, Business, and Enterprise users starting on October 7, 2026, while free and Go accounts received the update on October 8, 2026. Higher-tier subscribers gain access to the mid-range GPT-6 Sol model, whereas free and Go users receive the more efficient GPT-6 Luna. According to OpenAI, the new architecture allows ChatGPT to combine text, visuals, and interactive elements seamlessly while performing better web searches and providing quicker, partial answers while gathering information.
Instead of registering as referrals from the AI assistant, clicks were routed straight to web analytics tools as direct traffic.
Cedric Huesler noted the underlying technical change on LinkedIn, explaining that GPT-6 opens links with window(.)open(url, “_blank”, noopener,noreferrer
) and drops ?utm_source=chatgpt(.)com. He added that ChatGPT began opening links in a new tab with a browser setting that withholds the referrer, leaving off the citation tags.
Analytics Platforms Measure Immediate Referral Deficits
The tracking shift triggered immediate alarm bells across the SEO and publishing industries. Graphite CEO Ethan Smith reported that sites with meaningful traffic in the AI assistant channel saw their ChatGPT-attributed sessions in Google Analytics 4 fall by 22% to 57% starting October 9. Smith estimated this drop represented an approximate 45% fall from the previous baseline. Independent monitoring by LLM Pulse revealed a similar 46% reduction in sessions relative to the same days in the previous two weeks, even as total site traffic remained relatively constant during October 9 through October 11.
Further investigation revealed that mobile users absorbed the heaviest impact. Ninety-five percent of mobile visits to Graphite’s monitored sites relied exclusively on the tracking tag, leaving smartphone traffic completely exposed when the parameter vanished.
Tomek Rudzki at Peec AI ran an analysis across one million prompts from October 2 through October 7 and tested them again from October 9 through October 13 to measure the direct link changes. Additional SEO experts and platform observers, including Sébastien Billard, noted simultaneous drops in human and bot traffic associated with the platform.
OpenAI Deploys a Fix to Restore Traffic Attribution
Huesler later updated his observations to confirm that OpenAI addressed the behavior as a bug.
A corrective patch began rolling out early on October 15. By 9 a.m. PT, tagged ChatGPT clicks were back to roughly 95% to 100% of the same hour a week earlier, across thousands of domains tracked by Peec AI. SEO consultant Glenn Gabe noted that he wasn’t seeing the change yet on paid or free accounts.
Profound noted that while restoring the tracking parameters helps with future reporting, it cannot bring back attribution that was already permanently lost during the interim period. Meanwhile, competing platforms like Gemini took alternative approaches by adding UTM parameters to their links.