"Consciousness" is an overloaded thought killer that swerves all conversation into obfuscated semantic arguments. One person will be talking about 'internality' and self-image (in the testable, mechanical sense that you could argue Chain of Thought models already have in a petty way) and the other will be grappling with the concept of qualia and the ineffable nature of human experience.

That's not even a devil's advocate, many other animals clearly have consciousness, at least if we're not solipsistic. There have been many very dangerous precedents in medicine where people have been declared "brain dead" only to awake and remember.

Since consciousness is closely linked to being a moral patient, it is all the more important to err on the side of caution when denying qualia to other beings.