Every time I start a plasma session plasma shows a notification about the active network.
I am running 5.9 beta on Anch installed from kde_unstable repository.
That should be correct if I'm not mistaken, once you start a session then NM activates your connection and you get a notification about successful connect.
Closing as it seems to be correct behaviour.
This behavior is annoying.
I think the better behavior is show the notication only when the user enables the network manually.
*** This bug has been marked as a duplicate of bug 399973 ***