The button focus visual should not be displayed when you click on another button in the UI. Currently, because the toolbar has its own focus scope, it is possible to have the focus on the button and also on another UI element. This means that the button will have its focus visual shown.

To work this around you can extract the Template of the RadButtonStyle from the Telerik.Windows.Themes.Fluent.xaml file and remove the General IsFoucused setters (MultiTrigger). Then you can apply the style using the style selector of the toolbar. For your convenience I prepared a small example showing this approach. I hope that helps.

https://docs.telerik.com/devtools/wpf/styling-and-appearance/styling-apperance-editing-control-templates

https://docs.telerik.com/devtools/wpf/controls/radtoolbar/styling-and-appearance/style-selector