27 here ("Wow, you have excellent colour vision.") with fairly typical red/green colorblindness. I also fail the the Ishihara plate (dots) test like clockwork.

Does this test different hues (or brightness even?) of the same color rather than the red/green blue/purple of the dots? (Can't tell myself, am after all colorblind.)

This test seems to be about something else rather than traditional colorblindedness.