From a user experience perspective, this is well-thought-out and designed to enhance your viewing experience.
Well, there is a simple answer to this conundrum.
Head over the jump to change the Apple Notes background color on Mac with ease.
Hence, you have the desired flexibility to choose the method that is in line with your preference.
Change the Background Color of Specific Apple Notes on Mac
Voila!
Wrap Up… From what I can tell this slightly hidden feature works reliably.
