Are you sure you're running the monitor at its native resolution and not scaled? And do they provide a display profile that you can load?

Edit: This post would indicate that it's a bug in the interaction between the Mac and the monitor and is not fixed: https://forums.macrumors.com/threads/fuzzy-text-with-lg-38wn...

I am pretty sure I'm running it at the native resolution and not scaled, yes. At least, I'm pretty sure:

   > system_profiler SPDisplaysDataType | grep Resolution
             Resolution: 3840 x 1600 (Ultra-wide 4K)

And ah dang, thanks for the link. Someone there mentioned that getting a higher PPI monitor could help and might be the only way to get HiDPI modes. I did notice when I used switchResX for a bit that the HiDPI mode was greyed out and unavailable. Guess I'm going to have to return this monitor :(

matthew-wegner

BetterDisplay can get you supersampling on <4K monitors. I run a 4K monitor as my main display that did this out of the box with macOS, but I have side 1440p monitors that didn't. This fixed it: https://github.com/waydabber/BetterDisplay