Yeah, seems low to me. The multimillion dollar houses I think about when I think successful high-paying career for upper middle class seem to be out of reach for that income bracket.
I think your perspective is off. To me, "multimillion dollar houses" are upper class, not upper middle class.
People use "upper middle" to mean different things. Some use it to mean the upper portion of the middle class, by income. Others use it to mean a distinct (and much smaller) class between the middle and upper, with distinct tendencies and preferences, comprising people who live something close to a "rich" lifestyle but are distinguished from the actually-rich by having to work to maintain it, rather than being able to live a very nice life off investment income alone. Doctors, lawyers, other very-well-paid white-collar types, constituting perhaps a single-digit percentage of the population. I'm not sure which, if any, definition has a credible claim to being, in some sense, most-correct.
It depends on context. A household of two earners working for big techs living in a $2M home in Bay Area is definitely comfortable, but by no means upper class. Most of their incomes are still from a W2 form and they still have to budget for kids' school, retirement, etc.
Owning a $2M home in the most expensive area of the US is upper class.