It's so bright looking and I have a great TV for 4k gaming i switch back and forth between ps4/x1 on the HDMI to compare and the destiny 2 game just looks like poo, I guess people were right about 4k/medium settings it's just not utilizing something i guess. It's like brightness is set to max.
It could be something funky with HDR and/or game mode. To be clear, on PC in a Chrome window, Destiny 2 does look pretty bad. However, on a 4K TV with a Chromecast Ultra using a 4K stream, it should look pretty good. Not great, but not bad, either.
For my own setup, the key was ensuring my TV was both in game mode and processing HDR correctly. Before that, I had the opposite problem where it was far too dark. I can say that now Destiny 2 looks as perfect as it can at the resolution it is being actually rendered at.
I just tried D2 on stadia (PC chrome browser) and it's not good, nor smooth, I have 400 mb/s internet. just for comparison, I installed D2 via steam : woww so much better, definitely not playing on stadia.... sorry but it doesn't deliver.
For browser you will want the vp9 encoding enabled. If you don't have that, its not going to look great.
And makes sure that your extensions aren't causing lag, I found running in an incognito window to work the best. Good Luck!