Sistrix: ChatGPT's new answer format cut UTM tags and source lists in October

Sistrix, which queries hundreds of thousands of prompts a day in logged-out ChatGPT, says answers switched to a new block-based format (sections, images, comparison rows, expandable source tiles) overnight on October 8-9, in all six countries it tracks. The share of answers in the new format was 69-95% in the following days and 97-100% since October 23. In the same sample, utm_source=chatgpt.com was on 1-24% of source links from October 9 to 15 (42% on October 16) against every link before, and back on 99-100% from October 17; the end-of-answer source list appeared in 1-19% of answers from October 9 to 22, against about 72% before, and returned October 23 at 70-84%. Citations in the text stayed: 72.4% of answers had at least one source before the switch and 76.2% after, with linked pages per answer rising from 3.3 to 4.1. Sistrix says the model link is indirect: logged-out sessions at their limit have named gpt-6-auto since October 9, where GPT-5.6 appeared through September. The figures are shares of a random sample of its daily queries from September 15 to October 28, 2026; Sistrix sells the AI Check and Prompt Tracking tools that produce the data.