Based on Mac OS UI, when adding a task it is impossible to create a new label without using the mouse. You type the label and it gives you a place to click to say create new label, but looks like the only way to do it is to use the mouse to click on it. Tab takes you out of that field and erases that label you created. Would be nice to hit enter.
It was possible to to create tags by typing, but it was sacrificed in order to improve the search and completion UX. It would be nice to get it back somehow, but how often do you create new tags? For me, the answer is almost never. So it’s probably not worth the effort.
It is not a major annoyance, but something I noticed and thought worthy of reporting. My thought would be something like (on Mac) ⌘-⏎ (command enter or the equivalent on other platforms)
I should add that I do appreciate that it is easy to select tags by just typing the prefix and hitting enter (though for some reason I keep hitting tab instead of enter). I have used a system where it went the opposite way (I think it was Doit.im). If you had a tag of Computer and typed com enter it didn’t select Computer, it added a new tag called com.