SUMMARY

Whenever the computer is disconnected from the network (for instance, a wired connection or a wireless network), a notification is shown (which, I guess, is good).
However, if not dismissed, the notification is kept in the notification list and is shown as notification to be read. This is a very small annoyance but a network disconnection should not require the user to explicitly read and dismiss this kind of notifications. The user can see that they are not connected to this network by using the network manager icon.

STEPS TO REPRODUCE
1. Disconnect from a network
2. Do not dismiss the notification about the disconnection.

OBSERVED RESULT
The notification goes into the list of notification, marked as unread.

EXPECTED RESULT
The notification should simply go away, like notifications about joining a network.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: openSUSE Tumbleweed
KDE Plasma Version: 5.16.2
KDE Frameworks Version: 5.59.0
Qt Version: 5.13.0