aside from many/most of the backside thermal contact pads having anywhere from 25 to 50% of the thermal contact bumps not being there... Make nice jacks for pushing the board away from the sink.
Folks who still have miners unreturned can easily unbolt the heatsinks and verify this. If the bumps were such a problem to make properly then even a thin copper foil shim would have done the trick.
But when mechanicals/thermals are not assembled properly and you just keep putting power on unit after unit that was delivered working, you end up with a huge scrap pile.