Amazon Echo Flex: Microphone mute button appears to be real and functional
Disclosure: I'm an Amazon Devices PE, but not on Alexa devices.Jeff (and others) have spoken publicly about this in the past, and this teardown is correct.  The hardware is designed such that, if the privacy LED is on, the microphone is unpowered.  In order to compromise that, one would need to physically alter/damage the hardware.