You might notice in iOS 14 that the microphone indicator light is present even when you've muted yourself in an app. Apple says you shouldn't be concerned, as the indicator may remain active because the app still has a microphone session open, even if it's not recording any audio.
Apple's Craig Federighi, who oversees iOS, explained that in an email to a worried user who noticed the light was still on even after he had muted himself in a third-party app.
User experience concerns — While it seems intuitive that the light should only be enabled when an app is actively recording audio, there are usability concerns to consider. Some apps keep the audio session open so they can listen for commands that then trigger recording. Google Meet, for instance, will continue listening even when you're muted during calls so it can alert you should you begin to speak while your microphone is set to mute.
Federighi said that app developers may want to consider updating their apps to "shut down their audio sessions" when users have used an app-level mute button, so they're confident that the app doesn't have access to audio. It's possible Apple may require this in the future but Federighi doesn't say whether it will.
Apple can't really distinguish when an app is actively recording versus just keeping the session open. By keeping the light on whenever an app has open access to the microphone's stream, Apple is at least warning users to the possibility that a developer could be recording. Users can always go into the Settings app and manually disable microphone access for any third-party app if they want to be certain it's not listening.
Apple has come under a lot of fire for the control it wields over developers in its App Store, including imposing tough limits on data collection. It argues that its byzantine set of rules are intended to keep users safe from malicious apps. Critics say that by unilaterally controlling the only marketplace where users can download new apps, Apple is harming competition and raising prices.