I think there was a bit of a flap over that same issue two years or so
ago. Instead of being 0.2N NaOH solution, what was in the acid test
kits was nearly 0.4N, so all the acid measurements indicated there was
about half the actual level of acidity. The LD Carlson folks were
properly apologetic, claimed their supplier had messed up. But that
wasn't much satisfaction for those who had added lots of unnecessary
acid to their wine, based on bad measurements.

I decided at that point to make my own NaOH reagent, so I spent about
$10 and got a lifetime supply of NaOH crystals. 0.2N works out to 8
grams per liter, and a liter will last me a whole season or more. So
my couple of pounds of reagent should last me for about another
century or so of winemaking, assuming I keep it dry. :-)

Doug