Noteplan has used a few specific “types” of tasks to imply that a task has been deferred or cancelled for a few years, IIRC. At least, that’s why I was originally excited by the idea of a stylable data-task attribute.
@EleanorKonik also advocated for the data-task attribute not because of the use in tasks but because it served as a way of doing bullet journal-style notations, I believe. So bullet journaling is probably another precedent!