It is rather abysmal that photoshop still has this critical bug, given that is has been reported for years now. It is a software for professional imaging yet you cannot work on an image at print resolution and have accurate color displayed on the screen.
Steps to reproduce: -For full effect, open an image with dark shadows you would like to lighten -Again, to dramatize, we are going to add two curve adjusment layers --Make one curve to set your black and white points and your gray balance --Make another curve to open up the dark shadows -You should see that at 66.67 magnification you will get the true colors while at 50% below colors suddenly change, meaning you cannot look at the image as a whole and make color adjustments. This applies to any image that is more than 4/3 your screens total resolution, which, for a 1080p monitor that is beyond the average, would be 3MP. Yes, that is three megapixels as in DSLRs of 14 years ago.
Perhaps you could have an option to 'render proxy at this magnification' which would render a 16bit cache level at a specified magnification at which curves et al could be calculated from there on.
Shame on you for not having addressed this despite pleas from multiple professional fields for so long.
Photoshop 23.5 shipped with a new option called "Precise Previews for 16-bit files" in the Technology Preview Preference. It's on by default, and preserves 16-bit previews at higher image pyramid levels.