Red microphone symbol on Iphone X display - even when I don’t use my phone.

HI! I have a problem with my Iphone X. A red microphone symbol appears in the right corner of the display even when I don’t use my phone. It also appears when smb calls me via messengers. I checked my settings: only messengers have acces to my mic, no other app has it. but how the mic can be turned on when I don’t use the phOne. Does this mean somebody is recording me? Please give your advise what to do? and how to explain it? Thanks! Please find photos attached.