Do not change focus on buttonpress.
MODIFY
WalletWasabi.Gui/Controls/LockScreen/PinLockScreen.xaml
WalletWasabi.Gui/Controls/LockScreen/PinLockScreen.xaml
<Grid.Styles>
<Style Selector="Button">
<Setter Property="Margin" Value="4" />
+ <Setter Property="Focusable" Value="False" />
</Style>
</Grid.Styles>
<Button Grid.Row="0" Grid.Column="0" Content="7" Command="{Binding KeyPadCommand}" CommandParameter="7" />

Do not change focus on buttonpress.