I'm running dual 32" 4k displays. I'm also a Generalist (Photo / Video / CGI) and the issue of UI scaling within an app is only an issue with Resolve.
Here's the issue I'm experiencing with Resolve and using 4K displays...
- Windows UI scaling to 125 - 150% (recommended) is widely used by many people in many different industries and works well in both a practical sense and usability sense.
- A list of apps I use regularly includes: Adobe Creative Suite (PPro/AE/Photoshop/Illustrator), C4D, Zbrush, Substance, Modo, Blender, C1Pro, Kyno, PureRef, Mootools 3D Viewer. None of these apps have issues with UI scaling. Resolve is the only one that behaves poorly / oddly. In my opinion this should be top of the list in terms of Resolve's user experience to-do list.
I don't understand the push-back I'm seeing in the Blackmagic forums when users request a working solution to Resolve's UI scaling when using 4K (i.e. High Resolution) displays and Windows 10 scaling. Again, virtually every mainstream production app that I'm aware of resolved this

ages ago.
Follow-up: Let's assume that Windows scaling is being used by many production artists who work on 4K displays (which it likely is). When this is set to 125% and Resolve is set to 'Override high DPI scaling behavior' then Resolve's UI is far too small to read/use effectively. When Windows scaling is set to 150% (recommended) and Resolve is set to 'Override high DPI scaling behavior' then Resolve's UI is far too big to read/use effectively. When Windows (the System) is set to control the behavior of Resolve's UI then visually Resolve's UI scales to an expected scale, however the Clean Feed to a second display does not work (shifts to fill only 75% or 50% of the second display when Windows scaling is set to either 125% or 150%. Basically, Resolve's UI scaling needs some fine-tuning. This would make a big difference.