I keep hearing this, but not from the climate science community, but from laypeople. I don't understand it. I haven't yet heard reasonable physical mechanisms that would push us past 3C by 2050, when the mean expectation from major models is still ~2.7C by 2100.

We haven't even hit 1.5C yet, not as a running decadal-ish average, using "1.5C target" the way that climate scientists traditionally meant it. How are we going to add another 1.5C in the next 25 years? That'd require 0.65C/decade. I don't understand it. The math ain't mathin'.

For what it's worth, the link you cite talks about the reasons for the acceleration. But some of those reasons (El Nino, aerosols) lead to one-off pops that don't translate to higher long-term trends. Meaning, it would be reasonable to guess that the recent acceleration will taper off some, and we'll head back towards 0.2 - 0.25 C/decade from the current 0.35C/decade. But even if we keep up the current 0.35C/decade, we aren't getting to +3C until ~2075.