This is essentially a report of this issue here but for manjaro:
Which was resolved in these changes:
The following errors occur with every login with Manjaro ARM lxqt rpi3 19.04:
lxqt-panel: Show Desktop: Global shortcut 'Control+Alt+D' cannot be registered
lxqt-panel: Volume Control: The following shortcuts can not be registered: 'XF86AudioMute'
community/lxqt-panel 0.14.1-1 (642.3 KiB 3.4 MiB) [lxqt] (Installed)
Let me know if you need anymore information