Vincent from hdtest and friend evilboris made a video on Destiny 2 HDR brightness/dark issues and how to set things properly. Since OLED and Destiny 2 darkness issues go hand in hand for some people I thought I'd post it here.
It made my OLED perform better in dark areas and more details are visible now. Watch the entire 10 minute video to understand Bungie's dark/bright philosophy.
Bungie also fixed a few areas that had other issues with this last patch such as the IO LS and Nessus Failsafe entrances.
Summary: HDR dark/bright is based off of your SDR setting from pre-HDR Destiny, the 1 thru 7 box you selected in SDR Destiny settings.
-turn off HDR on your console
-start Destiny, go to settings, and set the brightness to 4 (default)
-turn on HDR on your console
-start Destiny, go to settings
-set the white-point as per instructions
-set the black-point exactly in the middle, 49 or 50 clicks from either side, try to find the exact middle.
Apparently a lot of games have created their HDR brightness/contrast profiles the same way so this may help in other games too. Watch the entire video to gain insight into Bungie's dark/bright philosophy.
Don't let Vincent's humor sway you if you're not familiar, his reviews and advice are top tier, he is well respected on AVSforums, etc.