I use a window manager, namely: https://github.com/nikitabobko/AeroSpace
It creates virtual workspaces and assigns windows to that workspace. After having Orion open for a while, there is a ghost window, you can see it in mission control:
notice that the icon is not centered - mission control centers over the group of windows because I have "group windows by application turned on"
This indicates to me that there is a second window to the left of the main one in my screenshot. This happens frequently, and the only way to restore Orion to a single Window seems to be by hard quitting with cmd+q and relaunching.
This causes me particular pain, as my window manager selects the ghost window when I swap back to that workspace, and a result, it doesn't properly switch to that workspace.
I expect that these ghost windows are never created and/or closed immediately when they are no longer needed.
This is what I expect the mission control to look like, i.e. no ghost window:
0.99.132
Catalina (10.15)