Running Brave 0.15.2 on Windows 10…
If Brave is maximized and in front, Windows taskbar is not on top. If Brave is restored to regular window, taskbar is always on top.
Normally, I only access the taskbar by navigating my cursor to it. Now the only way I can access the taskbar is to either press a key (combination) on my keyboard, or restore the Brave window from a maximized / full-screen state.
As of Windows 10, there is no user-configurable system setting to keep the taskbar on top of all windows. It is assumed as default.