The screen previously was only able to turn up to a brightness of 300 nits, according to Apple’s own spec sheet for the laptop. MacRumors confirmed that the Air’s screen brightness increase is tied to macOS 10.14.4, which first dropped back on March 25th.
macOS 10.14.4’s notes specifically state that the update “corrects the default screen brightness” for the 2018 MacBook Air.
There has been a bit of confusion regarding the original nits of the MacBook Air’s display, with real-world estimates landing somewhere between 234 and 315 nits of brightness.
Regardless, the lightweight laptop now features a display brightness of 400 nits.