WCAG 2.2 contrast ratio (never rounded up). AA: 4.5 for text, 3 for large text. AAA: 7. Rows are text colours, columns backgrounds; the last two rows are plain white and black text.
Simulated with Machado, Oliveira & Fernandes (2009) at full severity, in linear RGB; achromatopsia shows relative luminance. Colours that merge here can be told apart only by lightness.
As you see it
Simulated
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