SUMMARY
When I click RMB on minimized application I'm able to move it to another desktop or to another activity. Unfortunately I'm not able to move to another display.

This missing possibility is annoying in case when application starts on display which turned off (from some reason Plasma sees it). For example I run application and its windows is placed on desktop related with display currently turned off, because before I was running this application on another display.
What I can do then? 
I can turn on another display to be able to move its window to my currently working display. Or just move mouse cursor to invisible display (yes, it is possible) and blindly click holding Alt key trying to move caught (or not) window. :/

STEPS TO REPRODUCE
1. Connect another display (in my case it was projector)
   and let Plasma recognize and configure it.
2. Run some application (in my case it was vlc) and move it onto desktop related with connected display
3. Close this application and run again to be sure that is running onto desktop related with connected display
2. Turn off connected another display
3. Relogin plasma or restart your PC
4. Run again mentioned application 

OBSERVED RESULT
Running application (which remembered its place as another display) should be placed in invisible desktop on turned off another display. And it is OK.

EXPECTED RESULT
Possibility to move mentioned application by clicking RMB on its icon (placed on application bar) to currently working display or to any connected display.
Would be nice to have such option as next calling i.e. "Move To Display" after existing: "Move To Desktop" and "Move To Activity"

SOFTWARE VERSIONS
(available in About System)
KDE Plasma Version: 5.14.3
KDE Frameworks Version: 5.51.0
Qt Version: 5.11.2

ADDITIONAL INFORMATION