Inside the research
Some answers gave no visible credit
Four answers to the two general prompts in ChatGPT and AI Mode contained no visible citations. That observation describes the interface; it does not reveal how the answer was produced.
Specific questions changed the citation pattern
Price, location and current-information prompts showed citations in all three sampled tools. For the value-for-money prompt, eight of fourteen links pointed to independent reviewers.
Keep inference separate from observation
The title raises a question. An uncited answer does not prove training-data absorption, identify an uncredited source, or establish whether retrieval occurred. I would use the findings to design repeated citation tests, not to estimate lost traffic.