I've noticed that on the 24kw cars that the battery declines to ~90% SoH quite rapidly, then the rate of decline slows down. (the 12th bar on the battery gauge represents a larger % of SoH in order to linearize the scale). I've often though that they drop to ~22kw so rapidly that it would be more truthful to think of them as 22kw batteries.
Given that the 30 Kw batteries are still fairly new to the market, I wonder if they are still in this initial stage of rapid decline and simply haven't reached the point where they plateau and their decline slows. If so, this whole situation may be nothing to stress about. Perhaps Nissan has incorrectly estimated the point at which they plateau and correspondingly not set the 11 to 12th bar threshold correctly.
It might take another couple of years of using the 30Kw batteries to accurately establish their true characteristics.