Strange message : Steam update - KDE Daemon ??!!

[MegsOconnor]

Each time you start kde, a window with a notification icon (!) appears. This window with a rather suspicious design asks me to click on a button to update Steam. apart from the normal path, steam does not offer me an update and the last date is two weeks ago. When I search with xprop, by clicking on the notification I have no PID. and one in three times it crashes the system.

What can I do to find out if this is a legitimate request or something less nice?

wmctrl -lp -> "0x00e0000a 0 2067 FLY-ENGINE Mettre à jour les informations — KDE Daemon"