Most people seem to think that phenomenon is not the same thing. People have shown by experimenting with different prompts that even in Mandarin, Claude correctly says it’s Claude when it is doing something for you. But if you ask it about its identity, it sometimes says DeepSeek. The current theory is it just has run into Chinese content that has chat logs that often have a DeepSeek model answering that it is DeepSeek. But the inconsistency in different prompts suggests this is something different from distillation.

They most likely weren't, despite very dubious claims of Amodei and Altman and a certain twitter influencer running a pretty naive writing benchmark ("slop test") that is wrong in a very obvious manner. The only unambiguous cases of distillation were Gemini 2.0 experimentals being trained on Claude outputs, and GLM-4.7 being trained on Gemini 3.0 Pro. The rest are pretty different from each other.