Convey important information in multiple modes (sounds, haptics, colour, iconography, messaging...) so no-one misses it. Take Spotify's shuffle button. It is green when on, white when off, but it has also a dot indicator.

https://wearecolorblind.com/examples/spotify-shuffle-and-repeat-buttons/

Two sketches of the Spotify app. One of them has the shuffle button off and the other one is on. For the on state, it has a different colour, green, and it is also adding a dot indicator underneath the icon. It also shows how VoiceOver announces different states, on or off.