Can't use saturated colors as display background

[SacrificialClam]

I'm running into strange behavior when I try to set the display background to a simple color. If I choose a highly saturated color, such as black, for the background, FreeCAD instead uses a much lighter version of whatever color I choose. If I choose a light color, FreeCAD just changes it to white:

phpBB [video]

Update: not sure the embedded player is working. Video here: https://www.youtube.com/watch?v=AEKtmcSMOtI

In the video, you can see that when I do a drag select, the area outside of the select window is the proper background color. This behavior seems to be somehow related to the anti-aliasing options, though. If I turn off anti-aliasing entirely, this doesn't happen.

I was able to "fix" this by resetting all of my settings to the default, but I'd like to know what caused this in the first place so that it doesn't happen again. Any ideas?

Version info
OS: macOS 10.16
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.24276 (Git)
Build type: Release
Branch: (HEAD detached at 0.19.1)
Hash: a88db11e0a908f6e38f92bfc5187b13ebe470438
Python version: 3.8.8
Qt version: 5.12.9
Coin version: 4.0.0
OCC version: 7.4.0
Locale: C/Default (C)