When I try to adjust the volume, the TouchBar appears on my screen. I tried to refresh the TouchBar agent by killing it, it doesn't work. And another problem about this issue is I cannot smoothly adjust the volume, I have to keep my finger on a certain point, because a circle shows up and it needs to be full before recognizing a press. It looks like a debug mode, I have no idea how this happened.
My setup is: 2017 MacBook Pro with macOS Sierra version 10.12.6