Just setting opacity to show state is generally seen as bad practice, the difference in contrast is just too little compared to real life. Seeing as the screen is dimmable/ can be used in various lighting situations, if every switch is off it can be really hard to tell if the current opacity is 'all on' or 'none on'. In UX design it's common to see this solved by both using opacity but also a distinct shape/contrast and by changing the icon. Sometimes throwing a bit of color in can help those who are not color blind. Normally you'll see all three.

Ironically, you can see the team trying to solve this in material's filter chips by adding a checkmark: https://material.io/components/chips/#filter-chips