It’s rare, but every once and a while your MacBook’s Touch Bar can get stuck, showing you only one set of buttons and not responding to touch. For me it was displaying the “Unlock With TouchID” message long after I logged in, but it’s hypothetically possible for this to happen while running any application.
The quick solution is to force quit the application that’s stuck on the Touch Bar, but if that doesn’t do the trick, you can force the Touch Bar to “restart.” This should solve the problem in almost all cases.
First, open up the Activity Monitor: you’ll find it in /Applications/Utilities, or by opening Spotlight and typing “Activity Monitor.” Once you’ve opened the program, type the word “touch” in the upper right search bar.
You’ll find a process called “Touch Bar agent.” Click this, then click the “X” button in the top-left corner to force quit the process. The Touch Bar will go blank for a second, then re-launch, hopefully solving whatever hangup that caused it to freeze.