I noticed this in the macOS Mojave 10.14.4 update today
"Corrects the default screen brightness for MacBook Air (Fall 2018)"
https://support.apple.com/kb/DL1994?locale=en_AU
Does this fix the problem??
Maybe take a screenshot of your screen brightness prefs before running the update, to compare?
"Corrects the default screen brightness for MacBook Air (Fall 2018)"
https://support.apple.com/kb/DL1994?locale=en_AU
Does this fix the problem??
Maybe take a screenshot of your screen brightness prefs before running the update, to compare?