A recent change is that running gnome-terminal (the "Terminal" application) from the launcher now finds an existing window if one is open. In 18.04, doing this would always open a new terminal window.
This is really annoying. I typically have half a dozen workspaces open for different things, and when I try to launch a terminal, I want a new one on the workspace I'm on, not to be dragged to a different workspace that happens to have a terminal already open where I then have to create a new terminal window and drag it back to the workspace where I want it.
Is there some way to change back to the old behaviour?