I'm not sure if this is common knowledge, but I've had dull colors in Destiny 2 for a couple of years and just recently found out that the root cause was the Windows 11 Automatic Color Management (ACM) option. When this option is disabled, Destiny 2 once again looks like it should (and did when it was released) with vibrant, vivid colors. I run the game in HDR but the setting affects both SDR and HDR. Note: it seems that ACM auto-enables itself (and needs to be manually disabled again) every time you change color settings in the Nvidia control panel, like going from 8-bit to 10-bit color as one would when setting up HDR properly.