themeMode property
Determines which theme will be used by the Feedback UI. If set to ThemeMode.system, the choice of which theme to use will be based on the user's system preferences (using the MediaQuery.platformBrightnessOf). If set to ThemeMode.light the theme will be used, regardless of the user's system preference. If theme isn't provided FeedbackThemeData will be used. If set to ThemeMode.dark the darkTheme will be used regardless of the user's system preference. If darkTheme isn't provided, will fallback to theme. If both darkTheme and theme aren't provided FeedbackThemeData.dark will be used. The default value is ThemeMode.system.
Implementation
final ThemeMode? themeMode;