You may get an exception like
InvalidOperationException: The current thread is not associated with the Dispatcher. Use Invoke() or InvokeAsync() to switch execution to the Dispatcher when triggering rendering or modifying any state accessed during rendering.
or you may get components that simply don't work (for example, a Window does not show, a treeview does not expand).
The solution is to revert to the RenderComponentAsync method in your _Hosts.cshtml file.