It sounds like you have it set to All Spaces [Desktops].
With the app running & in the correct Space, right click it in the dock & select Options > This Desktop.
For a fuller answer on setting up & using Spaces, see my other related answers at https://superuser.com/a/1187552/347380 or https://apple.stackexchange.com/a/179403/85275
It is correct that macOS runs upon the kernel named Darwin that Apple develops. Its source code is available online.
However, it is not exactly a "distribution" of BSD:
If you compare it to Linux with the many distributions available, such as for example Ubuntu and Fedora Linux it's a completely different ball game here. They have a specific kernel ...
Deleting the .DS_Store file on the desktop could help. Keep in mind that all icon positions are getting lost:
Open the Terminal.app in /Applications/Utilities
enter "rm ~/Desktop/.DS_Store" without quotes and hit enter
Relaunch the Finder
Press and hold the opt key
Right-Click or Control-Click on Finder in the Dock (while still holding down the ...