There's both. With the web interface it clearly has stopwords or similar. If you run it locally and ask about e.g. Tienanmen square, the cultural revolution or Winnie-the-Pooh in China, it gives a canned response to talk about something else, with an empty CoT. But usually if you just ask the question again it starts to output things in the CoT, often with something like "I have to be very sensitive about this subject" and "I have to abide by the guidelines", and typically not giving a real answer. With enough pushing it does start to converse about the issues somewhat even in the answers.

My guess is that it's heavily RLHF/SFT-censored for an initial question, but not for the CoT, or longer discussions, and the censorship has thus been "overfit" to the first answer.