Whatsapp: voice message --> screen goes black (not related to proximity sensor)

When I listen to a Whatsapp voice message, my screen goes black. This does not have anything to do with the proximity sensor, as it happens when I am just holding the phone in my hand, in front of me (so nothing close to the proximity sensor). I am then not able to reactivate the screen, until the voice message has ended. Also, the volume of the voice message is very low.

Could someone tell me what to do / how to solve this?

Thank you in advance!

A post was merged into an existing topic: Blackscreen when playing a sound