Please Stop Using Grey Text. For over 1000 years black text on white… | by Andrew Somers | Apr, 2022 | Tangled Web

Conversely, as the WCAG 2 math does not consider human perception, that 4.5:1 can be more than enough in some cases. The fact is, relative to a perceptually accurate model, WCAG 2 manages to pass colors that should fail, and yet fail some colors that should reasonably pass.

人間の知覚を考慮すると、WCAG 2 で十分とされる 4.5:1 を満たしていても不十分であったり、逆に満たしていなくても十分な場合もある、とのこと。