You can also test it by yourself by changing the background of the Bottom Navigation to black.
What’s supposed to happen
The ripple when clicking on one of the options is supposed to turn the opposite darkness of your color. If your background color is light, the ripple should be dark, if your background color is dark, the ripple should be light.
It’s not a long way… this wouldn’t work for any of the components that have a ripple already (if the arrangement is clickable). It would also not work for a component that has children with ripples, for example the bottom navigation (it only works on dark backgrounds). The extension also doesn’t let you change the color, it’s just stuck on the default color like every ripple so it wouldn’t work anyway. The button touch color works, but not the cardviews.