Problem
UPDD Commander window keeps relaunching and popping up repeatedly and no apparent way to stop it.
Reason
That issue happens when UPDD Commander is launched as a normal application, even though it's been set up as an always-on background app that the system will keep launching.
If a new instance of UPDD Commander is launched while it is already running, the new instance triggers the settings window to open in the first and then quits. But since it is an always-on background app, the system will keep launching it every ten seconds.
To resolve, select "Quit UPDD Commander" in its menu bar icon. Afterwards, the system will relaunch UPDD Commander again, but this time that will be the only running instance and it will remain open normally.