Comment 35 for bug 1574079

> even if it doesn't happen by default in Kubuntu

GNOME autostarts gnome-software, which allows you to update applications *and* firmware on devices. The latter contacts fwupd for the list of updates which then itself autostarts the fwupd binary. If you call `fwupdmgr get-devices` manually on kubuntu, then insert the device you'll likely see the same symptoms.