Comment by mlukaszek
Terrible idea for color-blind people. And I don't even mean severely color-blind, like when you can't distiguish red from green at all, but something more common and less severe, like deuteranomaly - where it's shades of these colors that are hard to distinguish.
The color blind would still see the parenthesis at least like they see them currently without the color coding though, given they are distinguishable from the background by lightness.