Redmi Note8 Pro - getting a black screen while calling or listening a voice message at whatsapp


Feb 2, 2020
I have bought the Redmi Note8 Pro in December and have the MIUI Global 11.0.3 Stable / PEGGEUXM, Android 9.PPR1.180610.11 .
In the last few days the screen turns black when I make a phone call or listen to a voice message at WhatsApp. This happened even if I have not the phone near my ear. Normally WhatsApp would play the voice message automatically turning the speaker on, but the screen turn back and the message was in the "phone call modus" and not in the speaker. I don't know what happened, if there was any automatic app updates.
I have read many recessions of people having similar problem. Some recommended to check the proximity sensor. I searched for the word proximity or sensor in the setup, however nothing was found.
Some recession recommends to download and install the PEGGEUXM, which I already have.

Does anybody has any clue how to solve the problem?