They do not. That’s an extension (WebChatGPT), not ChatGPT native product. It literally says it there. The way this extension responds to your queries totally depends on the developer of it. It’s not OpenAI’s product.
Plus Bing Chat is not GPT 3.5. It’s GPT-4. They literally stated it yesterday.
Extension or not, there is a way for it to communicate with the web. And it does not make results any better. Plus , as far as I tested bing chat, it produces about the same reponses as chat gpt 3.5 when connected to the internet and the same responses as gpt 3.5 when you specifically ask from it not to search.(that is , it also makes the same mistakes).
So, at least until now, I don’t know what they stated, but GPT-4 is far superior in its responses(when not connected to the web) and bing chat looks like GPT-3.5 , actually dumbed down a bit compared to GPT 3.5 .
So, for me personally, right now it is either GPT-4 or personal human search of the web.