Acrylic fallback color
MODIFY
WalletWasabi.Fluent/Styles/Themes/BaseDark.xaml
WalletWasabi.Fluent/Styles/Themes/BaseDark.xaml
<SolidColorBrush x:Key="StatusBarControlBackground">#191919</SolidColorBrush>
<SolidColorBrush x:Key="StatusBarControlForeground">#A3A3A3</SolidColorBrush>
<SolidColorBrush x:Key="TextForeground">#FFFFFF</SolidColorBrush>
+ <SolidColorBrush x:Key="AcrylicFallbackColor">#1F1F1F</SolidColorBrush>
<Color x:Key="RegionColor">#FF212121</Color>
</Styles.Resources>
<StyleInclude Source="avares://Avalonia.Themes.Fluent/Accents/FluentDark.xaml"/>

MODIFY
WalletWasabi.Fluent/Styles/Themes/BaseLight.xaml
WalletWasabi.Fluent/Styles/Themes/BaseLight.xaml
<SolidColorBrush x:Key="StatusBarControlBackground">#ECECEC</SolidColorBrush>
<SolidColorBrush x:Key="StatusBarControlForeground">#777777</SolidColorBrush>
<SolidColorBrush x:Key="TextForeground">#212121</SolidColorBrush>
+ <SolidColorBrush x:Key="AcrylicFallbackColor">#E2E2E2</SolidColorBrush>
<Color x:Key="RegionColor">#FFFAFAFA</Color>
</Styles.Resources>
<StyleInclude Source="avares://Avalonia.Themes.Fluent/Accents/FluentLight.xaml"/>

MODIFY
WalletWasabi.Fluent/Views/MainView.axaml
WalletWasabi.Fluent/Views/MainView.axaml
<ExperimentalAcrylicMaterial BackgroundSource="Digger"
TintColor="{DynamicResource SystemAltHighColor}"
TintOpacity="1"
- FallbackColor="#1F1F1F"
+ FallbackColor="{DynamicResource AcrylicFallbackColor}"
MaterialOpacity="0.55" />
</ExperimentalAcrylicBorder.Material>

Acrylic fallback color