Why is my touch bar so buggy?
I'd imagine the Touch Bar can become buggy for the same reasons that any computer becomes buggy, so what you could do is use Touch Bar Simulator to see what your Touch Bar thinks it's displaying, thereby narrowing it down to if the issue is software or hardware. If it's software, try the usual stuff like disk repair and reinstalling macOS. If it's hardware, it may be time to visit an Apple Store...