Greyscale stops working upon opening built-in launcher

I installed Nova launcher, for obvious reasons.
Now, everything works fine after a reboot, and up until the point that I go into the built-in notes app to start using the included pen. Launching that notes app runs something, somewhere, that screws up grayscale in Nova. This makes every single app icon look like a black box. Strangely, the tiny icons in folders are shown as dithered (fake greyscale) instead.

I tried switching every refresh mode known to man, but only from the notification area button. If there is a setting buried deep somewhere I probably missed it.

Also note that this does not just affect Nova, it also affects the profile pics in the RiotX app. So it is more systemic than just a weird launcher app.

This still happens after the latest update (2020-04-09_18-53_2.3_7c5d74f)

In the latest build (2020-07-24), this is even worse as the issue begins at startup rather than waiting until I open the ContentBrowser app.

And I think this is the same issue, but all my images on Google Photos are washed out (seems to go to white rather than the usual black).

It took forever (until 10/16) for them to get back to me, but they finally did write back with a solution:

  1. Go to the Apps section of Content Browser
  2. For each app that is having this problem (for me, Nova and Google Photos):
  3. Right-click the app icon and click Optimize.
  4. Under Display, uncheck “Whiten Apps Background”.