ValidationAssist.Suppress does not affect textbox underline

I am using the following style to suppress validation on disabled textboxes.

    <Style x:Key="DefaultTextBox" TargetType="{x:Type TextBox}" BasedOn="{StaticResource MaterialDesignTextBox}">
        <Style.Triggers>
            <!-- Remove the errors when the control is disabled. -->
            <Trigger Property="IsEnabled" Value="False">
                <Setter Property="materialDesign:ValidationAssist.Suppress" Value="True"/>
                <!--<Setter Property="BorderBrush" Value="{StaticResource MaterialDesignTextBoxBorder}"/>-->
            </Trigger>
        </Style.Triggers>
    </Style>

Here is the result of that:

The red underline is still applied to the disabled textbox. The Error text is correctly hidden.

I worked around this by using the commented out setter for the BorderBrush. This is mostly just to make the behavior consistent with other controls. The Combobox does not require the workaround. I haven't tested any other controls either so it may be worth checking each one.

Inizia riproducendo lo stile XAML fornito con un TextBox disabilitato che presenta un errore di convalida, quindi confronta il relativo stile di convalida con il comportamento di ComboBox. Traccia il template o lo stile di convalida di TextBox e verifica che la soppressione della convalida rimuova anche la sottolineatura rossa, preservando al contempo il testo dell’errore nascosto.