The possibility that Covid deaths are over counted is real.
Sure. By how much?
Again, you have to get from 569K to 492K, you're already at 15.6% overcount. Maybe that's plausible, as I understand the excess death numbers are somewhat likely to end up around ~500K rather than 569K... But it still makes the 0.15% IFR implausible, because that assumes that everyone in the entire country has been infected with COVID, and I don't even come close to believing that.
Let's say we assume a number on the high end of possibilities, like 6x actual infections to official confirmed cases. That gets you to 190M actual people infected. I think that number is high, you may think it's plausible.
But for there to be an 0.15% IFR with 190M infections, that means that we've double-counted COVID deaths. It means that instead of 569K deaths, there were really only 285K deaths. I don't think we've come anywhere NEAR double-counting, and a number like 285K means we have to come up with explanations for why we're somewhere in the ~500K excess death range... Where did those extra 200K+ deaths come from, if not from COVID?
So with all of this, we have to throw out a number. I'm saying the number that screws all of these calculations is 0.15% IFR, so that number is the one I am most suspicious of.