Interesting to note that we've gotten this far without EUV kit, 7nm is still pretty impressive.
The number of machine learning steps needed to make a chip work at all with such small features is 4 or more generations, essentially we have long since (around 2002) lost the ability to know exactly why a given transistor goes where, or why a chip that works fine at 4.2 GHz fails either side of this.
I did recall that some newer chips are pre-screened at the factory using X-rays, presumably this is for aerospace and .mil applications where reliability has to be absolute.
Also recall that the newest memory is only ever powered up after all the chips have been assembled into a stack (see earlier) and often the yield can be as low as 60%.
That 256GB uSD has monstrous overprovisioning equal to 320GB, in fact 320GB isn't even state of the art now and getting the yields up was the reason 200GB and 256GB were spaced by five months.