Qualia are a hold over from a time when we didn't have the knowledge we now have, science and technology have long made the concept obsolete.
It arose from the idea that even if we explained everything about a red apple to a blind person they would still not be able to see a red apple, therefore there was something else that was the experience of seeing a red apple.
That argument was wrong in 2 major ways. The first was by thinking that our natural language (for example English) was up to explaining reality in anything like the detail and accuracy that would be necessary to describe "everything" about seeing a red apple. This is a common failing of many of the older philosophical "problems" they didn't understand the limitations of natural language to describe reality. The second was creating qualia from no evidence.
Today we know that the entire argument was wrong, because we have worked out how to describe a red apple* to a blind person to such a degree that they can "experience" seeing a red apple and we didn't need a single qualia to do so. We did this by using a language that better describes the world around us, mathematics. When the scientists connect up a camera to a blind person's brain they are describing seeing, and lo and behold someone has vision from "merely" having it described to them.
*to be completely upfront we aren't quite at the level of a red apple but this is now only a technological limitation since we have made blind people see, just not in a lot of detail yet.