Why does my iPhone show a red bar? Follow
Apple has designed iOS to help you understand your privacy. If an app is running in the background and using the microphone, iOS requires the top bar change to red, the same way it changes to green during phone calls. In scenarios where your device is connected via Bluetooth to your iPhone, the device's partner app will activate the mic on your phone to provide additional audio for any Yellow or Red Alert you start. To stop seeing the red bar, close the alert and your mic will deactivate.