navigationBarMutedUnselectedText property
If true, the unselected text labels in the NavigationBar use a more muted color version of the color defined by navigationBarTextSchemeColor.
If null, the default value depends on the navigationBarIsStyled value. If it is true, this property defaults to true, otherwise to false. If the property is defined, the defined value is used.
A muted unselected text color can only be applied when a defined text color has been selected. When navigationBarIsStyled this is always the case, but if it is false, you also have to assign a value to navigationBarTextSchemeColor or navigationBarSelectedLabelSize or navigationBarUnselectedLabelSize so a none standard TextStyle must be created that can be muted. If none of those properties are defined the widget default behavior for label text style is used, and unselected text cannot be muted since all properties are null.
Implementation
final bool? navigationBarMutedUnselectedText;