So hear me out. OneUI 5 is even less friendly than before in notification management and Samsung isn't gonna do anything to fix this mess because these aren't specifically "bugs" and these are intentional changes.
1. You cannot long-press a notification and see what category it is from. There's no way of knowing that anymore. Good luck trying to figure out in which category the app just sent that weird notification you don't want to see anymore.
2. You can't set a DND exception for individual categories anymore. You could, on OneUI 4.
3. Due to point #2 above, you cannot set DND exception to a notification from its notification settings anymore either, you need to go to the convoluted mess of DND settings > app exceptions. This is arguably not as intuitive as it used to be. It should all be available through an app's info page directly, especially where notifications are within the app info page. Further, the ability to add exceptions to specific categories has beencompletely removed, intentionally.
This is a mess, Samsung. You're becoming less and less like Android/Samsung and more like iPhone! If I wanted an iPhone I would have gotten an iPhone, not a Samsung! The only thing this is achieving is giving me less reasons to not get an iPhone instead of an iPhone wannabe that's more expensive than an iPhone.
The fact that you've done some of these intentionally and don't care about it, is concerning.
