Remember when Windows Research source code that was used for teaching in university, and was leaked in the late-aughts, way before Microsoft purchased Github?
I had this code in one private repository called "ms" for more than a decade. It didn't have Git history or anything, it was just some random files, plus the leaked sources.
I totally forgot about it until a last year ago, when I checked, and the code is entirely gone.
I'm now more careful about what I put in private repos. In fact I don't have anything private there anymore...