AppThemeBinding BarBackground with Brush in NavigationPage and TabbedPage not working

[AlleSchonWeg]

Description

Hi,
if you set a brush as BarBackground in a TabbedPage or in a NavigationPage Style with AppThemeBinding the colors are not changed if the user change the theme.
Sample:

  <TabbedPage.BarBackground>
    <LinearGradientBrush StartPoint="0,0"
                         EndPoint="0,1">
      <GradientStop Color="{AppThemeBinding Light=Red, Dark=Brown}"
                    Offset="0.0" />
      <GradientStop Color="{AppThemeBinding Light=Green, Dark=Yellow}"
                    Offset="0.5" />
      <GradientStop Color="{AppThemeBinding Light=Green, Dark=Yellow}"
                    Offset="0.5" />
      <GradientStop Color="{AppThemeBinding Light=Red, Dark=Brown}"
                    Offset="1.0" />
    </LinearGradientBrush>
  </TabbedPage.BarBackground>

  <Style TargetType="NavigationPage">
    <Setter Property="BarBackground">
      <OnPlatform x:TypeArguments="Brush">
        <On Platform="Android">
          <LinearGradientBrush StartPoint="0,0"
                               EndPoint="0,1">
            <GradientStop Color="{AppThemeBinding Light=Red, Dark=Brown}"
                          Offset="0.0" />
            <GradientStop Color="{AppThemeBinding Light=Green, Dark=Yellow}"
                          Offset="0.5" />
            <GradientStop Color="{AppThemeBinding Light=Green, Dark=Yellow}"
                          Offset="0.5" />
            <GradientStop Color="{AppThemeBinding Light=Red, Dark=Brown}"
                          Offset="1.0" />
          </LinearGradientBrush>
        </On>
        <On Platform="iOS">
          <SolidColorBrush Color="{AppThemeBinding Light=Red, Dark=Green}" />
        </On>
      </OnPlatform>
    </Setter>
    <Setter Property="BarTextColor"
            Value="{AppThemeBinding Light=Blue, Dark=Yellow}" />
  </Style>

Setting BarBackground={AppThemeBinding Light=Red, Dark=Brown} works.

Steps to Reproduce

• Open sample app
• Change theme dark/light via system settings

NavigationPage and TabbedPage background should change the colors.

I tested only Android. Please check also iOS if it works as expected.
Version: 8.0.90-ci.net8.24420.2
MauiApp6.zip

Link to public reproduction project repository

No response

Version with bug

Nightly / CI build (Please specify exact version)

Is this a regression from previous behavior?

Not sure, did not test other versions

Last version that worked well

Unknown/Other

Affected platforms

iOS, Android

Affected platform versions

No response

Did you find any workaround?

No response

Relevant log output

No response

[github-actions]

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[kevinxufei]

I can repro this issue at Android/iOS platforms on the latest 17.12.0 Preview 1.0(8.0.90-ci.net8.24420.2 & 8.0.80). The dark/light system theme changes, but the background color does no change.