They're defining upper middle class as " family of three earning $133,000 to $400,000 per year". So that's 2 middle aged adults + an adult child as the upper barrier.
What's that mean for your typical "family of 2"? Do they normalize on 3 incomes and play funny with the figures, using extrapolation for the third?
Because the cost of living has increased. $133k is going to just barely buy you a house in most of the country. Is starter home ownership "upper middle class"?
Absolutely not.
This is just inflation, and a disingenuous bullshit article in the NYT (as you can expect, at best). The middle class is markedly smaller, not larger, and they're just using old income brackets to define "upper middle class".