"yellow washing" is not a widely recognized or common term within the context of laundry or household activities. It is possible that the term has emerged or evolved since then, or it could be a regional or niche term that is not widely known.
If you could provide more context or clarify the specific area or industry where you've come across the term "yellow washing," I may be able to offer a more accurate explanation. As of now, I don't have information on a specific definition or meaning for this term related to laundry or general household practices.