Big Sur is all awesome with nice bells and whistles, but it completely screwed my two external 4K displays. Quick search revealed that I’m not alone, lots of people experience lots of different problems. Here is how I fixed some of them:
The 4K native resolution is no longer available
Back in Catalina, besides the very inconvenient “Scaled” Resolution there was an option to select the native 4K resolution. In Big Sur it’s gone by default and the “Scaled” version look plain ugly on 4K displays. In order to switch to native 4K launch the System Preferences (Click the Apple logo in the top left corner -> System Preferences), Open the Display properties and then click “Scaled” while holding the Option button. This will replace the standard “Scaled” options with the full list of resolutions. Select the topmost one.
I wish this “Option” trick work on the laptop’s own display, I’d love to put more information on it. Unfortunately holding the Option button only lets you to select the refresh rate, which is already set to 60 by default.
Also, some people reported that switching from USB-C to HDMI cables solved the problem for them. In my case the resolution fix worked fine with both the USB-C and HDMI.
Display is Not Being Detected
Actually both displays detected fine after the upgrade, but later one of them disappeared from the MacOS conciseness. That was a relatively quick fix, I just turned it off and then on again (unplug the cable, sometimes just pressing that power button doesn’t help).
Fonts and Icons Being Ugly
Even after I changed the resolution to native, the fonts, the edges of vertical lines and small icons in Chrome remained looking ugly. I had to restart Chrome with the updated resolution in order for these nitpicks to get fixed.
The Monitor Colors, Brightness and Contrast Do not Look Right
I do not know why and how, but Big Sur totally messed up with the monitors brightness. I had to manually readjust it for both monitors. The laptop’s own display somehow survived this.
The Night Shift Keeps Turning Off After Sleep
I didn’t find a good solution to this, but adding the night shift control to the menu bar (just drag and drop the monitor control from the Control Center into the menu bar) allows me to quickly turn the night shift back up when Big Sur forgets about it.
These are all problems I had with the 4K displays under Big Sur’s control so far. Besides these quirks and multiple bugs in the Music app I like Big Sur so far (both the OS and the real thing).