I saw a post from ifixit and there are lots of holes at the back of keyboard backlight. At first, I thought they were for screws but their position seems off. Or are they for ventilation?
Crd : https://www.ifixit.com/Teardown/MacBook+Pro+15-Inch+Touch+Bar+Teardown/73395
Crd : https://www.ifixit.com/Teardown/MacBook+Pro+15-Inch+Touch+Bar+Teardown/73395