This first came to my attention when I posted about some issues I was having in this thread: viewtopic.php?t=20122
I then discovered that RAW Power lets you view and change these hidden RAW Processing variables here. For the image shown in that thread Apple's engine was choosing a luminance noise reduction value of 0.81, completely ruining my picture. This can be corrected in RAW Power. But as far as I know there is no way to disable this in Pixelmator Pro (please correct if this feature already exists).
Thank you,
Logan