+15% performance increase over a 2080 Ti is something we've been hearing for a while. I don't see that necessarily being a bad thing as that would make it only about 10-15% slower than a 3080. Give it 16GB of VRAM and price it at $600 and it'll be a solid contender against the 3080 and would also likely persuade some prospective 3070 buyers to spend an extra $100 for double the VRAM and ~10-20% more performance.
Actually that is what coretek sources told him a while back and he hasn't confirmed anything else from him, but others do have deeper sources. Which is probably an AIB. MLID (Moores law is dead) and few others have said the Skew that has been leaking is not the top die. AMD has the top die in house and no one has access to it outside of AMD. Been keeping it close to chest. But the leaks are not of the top die because AMD is keeping that in house.