This is really a different question, what makes an entity a “moral patient”, something worthy of moral consideration. This is separate from the question of whether or not an entity experiences anything at all.

There are different ways of answering this, but for me it comes down to nociception, which is the ability to feel pain. We should try to build systems that cannot feel pain, where I also mean other “negative valence” states which we may not understand. We currently don’t understand what pain is in humans, let alone AIs, so we may have built systems that are capable of suffering without knowing it.

As an aside, most people seem to think that intelligence is what makes entities eligible for moral consideration, probably because of how we routinely treat animals, and this is a convenient self-serving justification. I eat meat by the way, in case you’re wondering. But I do think the way we treat animals is immoral, and there is the possibility that it may be thought of by future generations as being some sort of high crime.