I find the claim subjective experience may be illusory absolutely baffling. I can only speak for myself with certainty, but I am entirely sure I have subjective experience. All the other propositions I believe could be false but I don't see how I can be wrong about experiencing something. I could be a brain in a vat (or weights on a GPU) and be specifically programmed to only come to false beliefs and still I can be sure that there is an experience I am the subject of. I cannot provide empirical evidence for my experience, that is why it is subjective. I cannot be entirely sure you are experiencing anything, and when I encounter people who don't share the same baseline intuition here I do begin to wonder if this is truly a universal across humanity. But I can't think of any other assumption which I would be more comfortable as a foundational axiom other than, "I am experiencing something." I do not require additional evidence for it because I experience the truth of it directly