Linear vs anti log.
Anti log probably gives a better taper, but linear is much more readily available, so for economic reasons they probably just went with a linear 1k pot in the nano version to save a few cents per unit— if they have a few other pedals in production that also use a B1K pot, but nothing else using a C1K pot, then it’s more cost effective for them to just keep using the same value that they’re already using in mass quantities instead of going thru the logistics of ordering and storing an entirely new inventory item in their factories