According to Apple, touch Bar in the new MacBook Pro is basically a Retina screen that is controlled by a T1 chip running a modified version of watchOS. The Apple company chose this way of creating the Touch Bar to provide improved security, but also high performance for the new component of the MacBook Pro.
Although it has not officially acknowledged this, the Apple company has probably also implemented an ambient light sensor in the Touch Bar, which automatically changes its brightness. Basically, everything works in a similar way as what we have in the iPhone, iPad and iPod Touch, or even the Apple Watch, but that's normal, considering that the T1 chip runs watchOS.
Users cannot manually adjust the brightness of the Touch Bar while using the new MacBook Pro, so they have to rely on what Apple offers them. In this idea, in environments with a lot of light, the Touch Bar will have strong lighting, and at night the lighting will be of lower intensity so as not to affect the users' eyes.
We will find out more details about the automatic change of the Touch Bar brightness only after the new MacBook Pro will be officially launched by the Apple company, i.e. in 2 weeks.
"I wasn't able to try and trick it or confuse it, but the entire time I was using it—in a dark room and in a much more brightly lit one—it seemed to match the keyboard well."
