I have something strange happening: The list “Disks & Devices” from the panel opens sometimes by itself, and usually it happens when I have my USB connected to computer, but not mounted and opened in OS.
Why does it happen? Maybe the reason is that Manjaro shows me that list because I have unmounted USB and it wants me to do something with it?
I’d check, KDE System Settings > Hardware > Removale Storage > Removable Devices. Also can get there from a right click of the Disks & Devices applet.
Also, on a right click of the Disks & Devices (formerly Device Notifier — I have to keep reminding myself ), there is an option to “Show popup when new device is plugged in”.
The other place I might look is KDE System Settings > Personalization > Notifications.