XFCE desktop background from another monitor scaled

I have one external monitor
The laptop is 1080p and the external is 4k.
I dock the laptop and switch off the laptop screen.
After a suspend and resume, when the laptop screen is switched off, the wallpaper set on the laptop screen starts appearing as a PIP in the external monitor background (top-left)

This does not go off until either

1. the laptop screen is powered on (from xfce4-display-settings)
2. the laptop is rebooted.