A. Check if there are any Bluetooth devices connected to your iPhone that might be affecting the volume control. Disconnect any Bluetooth devices and try adjusting the volume again. If the issue persists, try restarting the app and your iPhone to see if that resolves the lag.

B. Adjust the volume using the physical buttons on the side of your iPhone instead of the in-app controls. If the lag continues, consider checking for any software updates for your iPhone in Settings > General > Software Update.