https://www.keithcirkel.co.uk/whats-my-jnd/?r=AG4mKP____6_

"This shouldn't be possible. I'm not saying that you cheated, but not not saying that."

0.0011. The quote seems a bit hyperbolic. There were maybe 2-3 that I didn't see and missed. 1-2 that I didn't hit perfectly but close enough. Display probably affects results (but didn't change any settings for this). I have a Dell IPS. I also moved my head around a bit, felt natural while trying to discern the colors.

I do have a good vision (including color). Reminds me of the other color-game where you order some colored boxes to form a spectrum.

Edit: just tried hard mode and got 0.0084. Missed maybe 3 that I couldn't see. Usually some magenta or blue colored. Grey and red / brown seem to be the easiest.