One design flaw with Vertical Tabs is how the selected pane switches from small icon to “close” icon. Often when there is substantial lag in Brave, delay in event processing tends to cause a “close pane” action in lieu of a “select pane” action.
Also, the tooltips tend to get stuck and overall the UX feels overly “twitchy” compared with other parts of Brave.
That said, it’s a great feature and I enjoy using it. Just trying to help improve here.