I use FF like is discussed at https://apple.stackexchange.com/questions/189138/restore-app-windows-to-their-original-spaces - a project per MacOS Workspace with a FF window on one or more. The current behaviour is for FF to re-open windows all on the currently open space. If I have many open (which I always do) then I need to manually move them to the desired space.
As discussed in apple.stackexchange, google Chrome supports NSWindowRestoresWorkspaceAtLaunch
So that it restores windows to the correct space. Could FF support this also?