"Whites" and "Blacks" behave wrongly in brushes and masks

This happens in all “local edit” modes, such as brushes, gradients, “select subject” etc.

In these tools, the “white” and “black” sliders behave weirdly, almost as they are editing a jpg. There is no latitude in the edit, even though it’s there in the original file: the same sliders, in the full image mode, work perfectly fine.

it’s much quicker to provide an example so I’ll attach screenshots.

https://imgur.com/a/rXdu48p (uploader not working today... I used imgur then)

as you can tell, in the screenshots on the right i can pull whites to recover sun spots, and push blacks to recover detail in the furniture. on the left, doing the very same edit with brushes, both whites and blacks are severely clipped. 

this has been happening forever, I’d love to see it fixed especially for recovering sun spots.