Fix: There are 2 plastic "stops" that crack over time and these things "snap" into the brake pedal arm to depress the switch.

One switch is for your brake lights and the other switch is for your cruise control.

I believe the upper pad is for the brake light and the bottom is for the cruise control. So if either of these crack and fall to the mat you will see plastic pieces on the floor.

Fortunately you can order these parts on Amazon for ~$5 for four and can replace them yourself. Note: the upper one is barely visible.

The part number for my 2004 FX45 is #46584-5P010. So double check your part number for your make and model, but any car older than 10+ years is subject to this part cracking and causing these problems.

Infiniti sells this part for $15-$20 each. (What a shame.)