Hey there Rustam_Himadiiev,
To clarify, does this only happen in one particular app or do you notice issues with the headset in other apps using the mic and ear piece?
If this only happens in one app, double check to make sure the settings for audio are set up properly, then follow these steps if more help is needed:
1. Close and reopen the app
Force the app to close. Then open the app to see if it works as expected.
2. Restart your device
Restart your iPhone or restart your iPad. Then open the app to see if it works as expected.
3. Check for updates
To see if updates are available for the app, open the App Store, tap your profile icon, then scroll down to see if updates are available. If updates aren't available for the app, update the software on your iPhone or iPad.
4. Delete the app, then redownload it
Delete the app. When you do this, you might lose data that was stored in the app. Then redownload the app. Then check to see if the problem with the app is fixed.
If an app on your iPhone or iPad stops responding, closes unexpectedly, or won’t open
Should this persist with the app, contact the app developer.
Take care!