My dad is colorblind, and the red off/green on looks the same to him; the slight shadow showing the side the toggle is on often isn't dark enough to be obvious,

My dad is colorblind, and the red off/green on looks the same to him; the slight shadow showing the side the toggle is on often isn't dark enough to be obvious, especially when someone gets cute and makes the slider pill-style (the button part takes up exactly half the space, with a vertical line down the middle). I expect this to be less common with mobile OS downtime features that encourage users to get off their screens by going grayscale.