The information about what built-in lens profile is being applied is new to ACR 8.4, but the application of built-in lens profiles is not new.
Whether those lens profiles do a perfect job is another matter, of course. And just like in previous versions, you cannot turn the built-in profiles off, but if someone creates an external profile those can also be applied.
The one thing to be careful of is if the built-in lens profile also corrects the same aspect as the external profile, for example, vignetting, then it’ll get double-corrected and the way to avoid this is to set the manual strength setting of that profile correction parameter, either vignetting or distortion, to its minimum value, effectively turning off the external profile’s contribution.
Ah, excellent info. Thanks. I just noticed another bit: for the 18-55 and 55-200mm lenses, the info box is slightly different and mentions "correcting distortion, chromatic aberration, and vignetting." I'll have to see what the 35mm says.
There are corrections for geometric-distortion, vignetting and chromatic aberration that can be housed in a lens profile. If some of those are removed then the profile only corrects for the others.
Recently, I think Adobe has tried to make their built-in corrections match whatever the camera is doing to the JPGs, perhaps using exactly the same formulas and parameters, even, if the manufacturer has cooperated in the process.
The lens without distortion correction is a fixed-focal-length lens, right? If so that lens can be optimized for minimal geometric distortion.
The zoom lenses are less able to be optimized so it would make sense that geometric distortion is corrected for them.