Record button misuses red
Currently, the record button uses red, a color usually meant to represent a destructive action in the context of other GNOME apps. This seems to be a leftover from a somewhat archaic pattern used in physical devices with record buttons; as it used to be tied to physical media, it was meant to warn users that using the function may erase critical data when overwriting.
Due to the modern digital nature of recording, however, there is no need to warn to such an event. Digital recording adds a new file without any other undesirable/irreversible modifications. I suggest that the button's color be changed from the "destructive" red to the "affirmative" blue, as it is a productive action as well as the main action of the application.