Different theme behaviour on physical phone (Xamarin)

The default theme applied to my xamarin android project displays different on a physical phone than on an emulated phone.

I have not changed any style beside some overrides for android.
As far as I am aware, the controls are shown and usable, only the colors are wrong.

I also have published the app via APK and installed it. So no debugger attached or anything, just plain installation. Same result though.

Emulated:

Physical:

This is my login View:

<ContentPage.Resources>
    <Style TargetType="{x:Type Label}">
        <Setter Property="Margin" Value="4,0,0,0" />
    </Style>
</ContentPage.Resources>

<ContentPage.BindingContext>
    <vm:LoginViewModel />
</ContentPage.BindingContext>

<ContentPage.Content>
    <Grid Padding="20">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="*" />
            <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>

        <StackLayout>
            <Image Source="teleport_foundation_logo.jpg"
                   Margin="0, 20, 0, 50" />
        </StackLayout>

        <StackLayout Grid.Row="1"
                     VerticalOptions="StartAndExpand">
            <Label Text="{Binding UsernameTitle}" />
            <Entry Text="{Binding Username}"/>
            <Label Text="{Binding PasswordTitle}" />
            <Entry IsPassword="True"
                   Text="{Binding Password}" />
            <StackLayout Orientation="Horizontal"
                         HorizontalOptions="StartAndExpand">
                <CheckBox IsChecked="{Binding SaveUsername}" />
                <Label Text="Remember username" 
                       VerticalOptions="Center"/>
            </StackLayout>

            <StackLayout Orientation="Horizontal">
                <CheckBox IsChecked="{Binding ShowAdvanced}" />
                <Label Text="Advanced options"
                       VerticalOptions="Center" />
            </StackLayout>
            <Grid IsVisible="{Binding ShowAdvanced}"
                  Margin="0, 10, 0, 0">
                <StackLayout>
                    <Label Text="Server Address" />
                    <Entry Text="{Binding ServerAddress}" />
                </StackLayout>
            </Grid>
            
        </StackLayout>
        <Button VerticalOptions="Center" 
                Grid.Row="2"
                Text="Login" Command="{Binding LoginCommand}"/>
    </Grid>
</ContentPage.Content>

My App.xaml:

<Application.Resources>
    <ResourceDictionary>
        <Style TargetType="{x:Type Label}">
            <Setter Property="Margin" Value="3, 0, 0, 0" />
        </Style>
        <Color x:Key="Primary">#1976D2</Color>
        <Style TargetType="Button">
            <Setter Property="TextColor" Value="White"></Setter>
            <Setter Property="VisualStateManager.VisualStateGroups">
                <VisualStateGroupList>
                    <VisualStateGroup x:Name="CommonStates">
                        <VisualState x:Name="Normal">
                            <VisualState.Setters>
                                <Setter Property="BackgroundColor" Value="{StaticResource Primary}" />
                            </VisualState.Setters>
                        </VisualState>
                        <VisualState x:Name="Disabled">
                            <VisualState.Setters>
                                <Setter Property="BackgroundColor" Value="#ffe6e6" />
                            </VisualState.Setters>
                        </VisualState>
                    </VisualStateGroup>
                </VisualStateGroupList>
            </Setter>
        </Style>
    </ResourceDictionary>        
</Application.Resources>

And Accent Color override on Android (styles.xml):

<style name="MainTheme" parent="MainTheme.Base">
  <item name="colorAccent">#1976D2</item>
</style>

This is my first real xamarin project, so any input is appreciated!