Yugou Foaming Sink Drain Cleaner Deodorizer& Clog Remover (Lavender, 2pcs) | Yugou Foaming Drain Cleaner, Sink Cleaner and Deodorizer, Drain Clog Remover for Kitchen Sinks, Shower Drains, Tubs

It was something like this but a random Instagram purchase. Thinking back, I can’t remember if it was a specialized product for the overflow specifically or if the gunk coming out of it was a side effect of the foam going down the drain and back up the overflow. I used the foam, scrubbed as best I could with a straw cleaner (which I threw away after), and finished with super hot water poured down the overflow. I redid it a couple times until a q tip came out clean. I really never thought I’d need to clean that part of my home, so I hope this helps someone lol. Try to take a picture to see if yours is dirty before getting paranoid about it.