The audio / video quality of the communication between App and your connected product is monitored during the audio/video communication and a red warning will appear at the top of the screen if this quality is low. 
In case it is shown during your calls it is necessary to check the quality of your ADSL / FTTC / FTTH connection and the 4G / 5G signal on your smartphone.
Also check streaming devices on your network as they could affect network performance.