I never had the case, that an URL did not exist. For me it shows stuff like "generating web search", so I guess it tries to fetch the URL first, before suggesting it. LLMs like to give tangentially related links, but this is typically paired with a sentence, that the link I really asked for, does not exist.

> It's impossible to have used LLMs for this purpose for more than a quarter of an hour and not have seen this.

You may be generalizing too much from your experience.