We don't even know how to disprove that this statement with "AI" replaced by "other humans" other than by listening to people self-reporting and taking their word for it and/or defining the words in ways that do not rely on a subjective experience.
Until we know how to objectively measure if someone or something is conscious, it seems unreasonable to make statements with any kind of certainty about it.
Sure, if you take a materialist empiricist perspective, which is myopic at best. As humans we have the unique and wonderful ability to know truths by themselves. Machines do not have minds, and they can not.
What sort of action does that lack of understanding actually motivate, though?
I don’t know if LLMs are conscious or have subjective experience in some philosophical sense. Sure, I don’t know that about other humans as well, rigorously speaking. But I also don’t know that about coffee machines, rivers, videogame NPCs, or even rocks really. (List ordered, of course, by the degree to which I’m willing to be convinced).