The root cause of the problem is the Walmartization of the
market which constantly drives manufacturers to seek ever
lower product cost, at the expense of product safety, environmental
disruption, perhaps slave labor in Asia, and product quality in general.

By all reports this manufacturer was trying out a "new ingredient"
from a "new supplier" (neither of which they will identify), and in
their test food runs nine animals died.  Unfortunately, the
"new ingredient" had been used in much smaller fractions for the
past few months.  In a way we're lucky they caught it at all.

Why were they trying out a "new ingredient" instead of sticking
with a known safe product?  My first guess would be that it's
cheaper.  Manufacturers of all retail products are under the gun in
a race to the bottom to produce the cheapest possible product.

Hopefully there will be some repercussions, and maybe next time
the manufacturers will be more cautious about changing things.

In any case, your kitten is probably okay: cats are one of the
few animals that can fully recover from kidney damage.  But have
your vet check look into it if you're able to do that.

Steve