Once you remove the PCB from the faceplate you'll have access to the RGB LEDs that make up the center button light.

Cut to size whatever you're using to dampen the LEDs, and apply them to each of the 4 LEDs.

In the image example, I'm using blue painters tape simply for demonstration purposes. Please note this is not strong enough to meaningfully dampen the light from these LEDs. When you perform this use something stronger.