They're likely changing it because security researchers pwned FALCON.
There is a way to leak the hash against which High Security mode FALCON compares the microcode for signature validation.
So hopefully you'll forgive me if I maintain my skepticism over this being anything but Nvidia iterating to close a massive security defeat by redesigning their FALCON controller to mitigate the thorough pwning that's been achieved.
I don't doubt there are other improvements, I just think the timing is pretty darn convenient, especially for being in the midst of a semiconductor shortage for going and doing a massive manufacturing change like that.