Hey there, LT012.
Welcome to the Apple Support Communities! Thanks for posting about the new notification that you're seeing when using an app that uses the microphone. We'd be glad to help you out.
You mentioned that you turned off the microphone for all apps in the list in Settings > Privacy > Microphone. One app that you likely won't see in that list is the Phone app, which is what you use when handling normal phone calls on an iPhone, so you're seeing the orange light because the Phone app is using your microphone while you talk on the phone. This is expected.
More info about this new feature are available in the "Review or change access to the camera, microphone, and other hardware features" section of Control access to hardware features on iPhone.
Let us know if you need anything else.
Be well.