I don't think this is Navi 21 i think it's more likely to be Navi 22 or 23.
AMD are so tight lipped that i doubt many have solid info on 21 and are very aware to keep their mouth shut, it's so hard to find anything solid to go by.
I'm expecting good things, i could be wrong, but it could be really a lot better than people are thinking and even the leakers most likely have it dead wrong, like some of the info put out on Nvidia's cards sure some of it was right but the important parts were totally wrong.