remove override ControlCornerRadius.
MODIFY
WalletWasabi.Fluent/Views/NavBar.axaml
WalletWasabi.Fluent/Views/NavBar.axaml
</UserControl.Styles>
<DockPanel Margin="0 0 0 4">
<StackPanel DockPanel.Dock="Top" Spacing="5">
- <StackPanel.Resources>
- <Thickness x:Key="ControlCornerRadius">0</Thickness>
- </StackPanel.Resources>
<Panel Height="40" IsVisible="{h:Platform {x:Static h:Const.False}, Osx={x:Static h:Const.True}}" />
<Button Classes="NavButton" Command="{Binding GoBack}" Background="Transparent" IsEnabled="{Binding IsBackButtonVisible}">
<PathIcon Data="{StaticResource arrow_left_regular}" Width="16"/>

remove override ControlCornerRadius.