Pelosi’s seemingly damning factoids come from the year 2027, an odd date to focus on, since it’s not when the bill goes into effect, but when part of it lapses. In 10 years, many of the tax cuts on the individual side expire. This means that the middle-class tax cuts go away, which Pelosi portrays as a Republican plot to loot the middle class.
It’s a very strange argument against passing a bill to say horrible things will happen once the legislation no longer fully applies. This is more logically a case for extending the bill than for blocking it. Indeed, it is almost certain that the middle-class provisions would eventually be preserved. (This is one reason Republicans were willing to let the individual tax cuts sunset and not the corporate tax cuts.)