OpenAI fixes ChatGPT UTM bug, but GA4 history stays broken

From roughly October 8 to 15, 2026, links in ChatGPT answers often lacked utm_source=chatgpt.com and did not pass an HTTP referrer, so many visits were recorded as Direct in GA4. OpenAI called it a bug and began rolling out a fix on October 15, but historical reports for that window remain inaccurate.

• ChatGPT links lost utm_source=chatgpt.com and referrer from Oct 8 to 15
• Affected visits were misclassified as Direct traffic in GA4
• Fix began rolling out Oct 15, tagged clicks returned to prior levels
• Historical GA4 data for the period cannot be retroactively repaired