In the case of liquid sublimation inks, they do have a specific shelf life, and after that, their shades maty fade or emulsify. In both cases, the ink’s effectiveness is lost, so the printer does not give better color due to the ink.
So, keeping the ink in the printer for a long time can be very harmful and may cause head clogging, color shifting, and banding. However, all of the inks have expiry dates mentioned on them. But it is always recommended to use the inks before six-month period.