I have an iPhone X running iOS 12.1.2.
I find when I pull it from my shirt pocket it has often been "working" itself, I will be in some random app. Sometimes that results in a pocket dial or FT call, sometimes I'm in Messages with gibberish typed in, etc.
FaceId is turned on and the screen lights up when I look at it, so why is it going active in my pocket? Is there any way to stop this? It's very annoying.