[M3/Top App Bar] Top app bar continues to display drop shadow when elevated

[OxygenCobalt]

Description: The top app bar continues to cast a drop shadow when using the Material3, against what the design guidelines say.

Expected behavior: The intended behavior should be for the top app bar not to cast a shadow, as the Material Design 3 guidelines state.

This is how the top app bar should look [note the lack of drop shadow]:

This is how the top app bar [with AppBarLayout] looks in my app right now [note the drop shadow but pastel elevation]:

Source code: I generally use this setup when making a top app bar:

<androidx.coordinatorlayout.widget.CoordinatorLayout
    android:id="@+id/coordinator"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="?attr/colorSurface"
    android:orientation="vertical">

    <com.google.android.material.appbar.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="?attr/colorSurface"
        android:clickable="true"
        android:focusable="true"
        app:liftOnScroll="true">

        <com.google.android.material.appbar.MaterialToolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:navigationIcon="@drawable/ic_back"
            app:title="Title" />

    </com.google.android.material.appbar.AppBarLayout>

</androidx.coordinatorlayout.widget.CoordinatorLayout>

Android API version: API 32

Material Library version: 1.5.0 [tested with 1.6.0-alpha02 as well, same thing occurs]

Device: Pixel 5 running Android 12

[dsn5ft]

@OxygenCobalt thanks for reporting this issue. Currently shadows are only removed from Widget.Material3.AppBarLayout and Widget.Material3.Toolbar.Surface, but I think we may remove them from the default toolbar style (Widget.Material3.Toolbar) as well.

However, I am sort of curious because you are using AppBarLayout and MaterialToolbar without setting any styles, which means they should be inheriting the default styles. The default styles don't set any elevation, so I'm wondering where that is coming from. Are you using an M3 app theme? Are you setting the elevation programmatically?

[OxygenCobalt]

@dsn5ft Looking into this, I don't see Widget.Material3.AppBarLayout being applied by default at all. Instead I see the M2 primary-color style used instead. That's why I have android:background="?attr/colorSurface" set on the AppBarLayout so I could get around that issue.

Removing that attribute and explicitly setting the style to Widget.Material3.AppBarLayout seems to work. This is likely a issue with the library, but I can't really determine the why since some strange usages of the old style may be around for compatibility.

[dsn5ft]

Can you confirm what app / activity theme you are using?

[OxygenCobalt]

@dsn5ft Theme.Material3.DayNight.NoActionBar