Originally Posted by @home
I think it was more to do with Google search somehow. But it only happened on this device & even when I had nothing else installed.
Well, I had a similar issue, except the phone would shut off after saying my password. (It will prompt you to say or type your password if you have one set). I forget what the problem was(I think it was something to do with a combination of immersive mode, windowed apps, and altered DPI settings) but even after uninstalling & wiping it still persisted. I ended up having to wipe the device & start over to get rid of it. So, there's that.