If voice recording works in one place but not inside a specific app, the microphone hardware may be fine and the problem may be permission or app-specific.
Check microphone permission
Open iPhone privacy settings and review which apps are allowed to use the microphone. Enable access only for apps you actually expect to record audio.
Close and reopen the affected app
After changing permission, fully close the app and open it again. If the app still fails, restart the iPhone before making broader changes.
Test a built-in recording feature
Use a normal built-in recording feature to confirm that the microphone can capture sound. If several unrelated apps fail, the issue may be wider than one app.
Keep privacy in mind
Microphone permission gives an app access to audio while it is using that capability. Review permissions periodically and remove access from apps that no longer need it.