Korean kombucha, a fermented tea extract, is included in modern cosmetic formulas for its sensory and skin-comfort properties, even in rinse-off products like cleansers. Its primary role here is not to deliver a lasting treatment effect, as it is washed away, but to improve the immediate experience of cleansing.
Specifically, it helps to make the formula feel gentler and more balanced on the skin during the brief period it is in contact with your face. It can contribute to a fresher, less dull appearance post-cleanse by supporting the skin's immediate look and feel. Think of it as a component that tempers the cleansing process, aiming to prevent that overly stripped or tight sensation that some stronger foaming cleansers can cause, especially when combined with an active like salicylic acid. It's part of the formulation philosophy to create a product that is effective at cleansing problem-prone skin while attempting to maintain a degree of comfort and skin balance.