"Follow system" theme setting follows system theme as it was on app launch

[Tarik-B]

Steps to reproduce:

• Put system in dark mode
• Start the app, go to settings
• Switch to "follow system" theme mode (whatever the previous value was)
• App now uses dark mode
• Change system theme to light mode while keeping the app launched

Expected result:
App switches to light mode

Actual result:
App stays in dark mode until restarted

[Tarik-B]

Official doc: https://developer.android.com/develop/ui/views/theming/darktheme#kotlin

Dark theme guides:

• https://medium.com/@kyawlinnthantkyawlinnthant/android-dark-theme-in-the-easiest-way-e82806c7331c
• https://medium.cobeisfresh.com/how-to-implement-day-night-mode-in-your-android-app-2f21907f9b0a
• https://medium.com/androiddevelopers/appcompat-v23-2-daynight-d10f90c83e94

Others:

• https://medium.com/@saishaddai/how-to-know-when-youre-using-dark-mode-programmatically-9be83fded4b0
• https://stackoverflow.com/questions/64168632/appcompatdelegate-mode-night-follow-system-not-working
• https://www.reddit.com/r/androiddev/comments/bu6ueh/how_to_get_system_current_night_mode_setting_when/
• https://stackoverflow.com/questions/55787035/is-there-an-api-to-detect-which-theme-the-os-is-using-dark-or-light-or-other