> When transforming text color, Adaptive Dark Mode aims for sufficient contrast as defined by the WCAG 4.5:1 contrast ratio.

The WCAG 2 contrast checker is known to be inaccurate, specifically for light on dark color combinations (i.e. dark mode) meaning 4.5:1 isn't always going to be easy to read so it's surprising they're not at least using a higher ratio. The APCA contrast checker (was being considered for WCAG 3) is more accurate at measuring readable contrast levels and the docs explain the problems with WCAG 2 more:

https://git.apcacontrast.com/documentation/APCAeasyIntro.htm...