That's the suggestion I give to designers so don't take this as criticism, but monochromatic contrast isn't perfect either. Some forms of colorblindness actually experience a shift in luminance that depends on the color and their specific perception. Things that are distinguishable by contrasting brightness (e.g. black text on white background) may become ambiguous if those colors are changed to e.g. green and red respectively, even if the lightness contrast remains the same because they'll perceive the red as darker than it truly is.

This is specific to the person, so there's no real way fix for everyone beyond turning everything into extreme differences like pure black and white. It's just something to note about the limits of it as an accessibility technique.

Red gives me nightmares, ugh. I hacked up my personal version of our algo to only pair it with white