We don't really have a good way to measure whether something has consciousness. Heck, we have pretty limited ways of testing how "intelligent" non-human animals are (e.g. https://en.wikipedia.org/wiki/Theory_of_mind_in_animals).

With that said, just because we don't have a great way of measuring it doesn't mean that we should assume LLMs are intelligent. An LLM is code and a massive collection of training weights. It has no means of observing and reasoning about the world, doesn't store memories the same way that organic brains do (and is in fact quite limited in this aspect). It currently isn't able to solve a problem it hasn't encountered in its training data, or produce novel research on a topic without significant handholding. Furthermore, the frequent errors made by it suggests that it fundamentally does not understand the words that it spits out.

Not really sure what you mean by your anesthesiology comment. Being able to intubate and inject propofol does not make you more of an expert on consciousness than neuroscientists and neurologists.

IMHO consciousness is just the ability to detect change. Everything can be calm and static, and then, suddenly, something changed. I think that is our capacity to notice that change that makes us conscious.

It's literally the only thing you can be certain of, your own conciseness.