What you see is not what you get.. image on screen is not correct when working in 16 bits image mode

I came across an error is the way an image is displayed; this used to be OK in previous versions, but now the image shown is incorrect.

The problem can easily be re-produced following the follwing steps.

1. Open a good quality raw image of a sunset (every one has one in her/his collection). See screenprint 1
2. Set the image mode to RGB 16 bits
3. Duplicate the background image.
4. Add 2 times a brightness/contrast adustment layer on top, set both to maximum brightness +150
5. Add 2 more brightness/contrast adustment layer on top, set both to minimum brightness -150
6. These 4 layers should cancel each other out.. So with perfect color depth and flawless calculations you should see an image that is the same (or very close to the original). However, I see on screen an image that is siginicantly different in colour, brightness etc. See screenprint 2
7. Now the strange thing.. If you force Photoshop to calculate, the image 'pops' back to be close to the original. You can do this (preferably) to merge the copied back-ground with the 4 adjustment layers, or to flatten the image. see screenprint 3
   
   

The image after step 7 is how it should look before step 7. After all, flatting an image should not change the way it looks. Now if you repeat the same steps with the image mode set to RGB 8 bits and do exactly teh same steps I find that the image after step 6 looks exactly the same as when I started with 16 bits. however, after step 7, it stays that way.

So this inicates that even when I work in 16bits mode, the image I see on the screen is calculated in 8 bits mode. This seems to be a serious bug, as we the image we see on the screen should reliably show all the modifications we have made to an image.. Withoug merging thos layers, I would have no clue how the final image would look like..

I work on a new macbook air with teh M1 chip set running big sur 11.6.

My photoshop version is 23.0.0