Elon Musk has recently made the announcement that likes have become private. But this isn't entirely true. You still receive "This person likes your post" notification which shouldn't be possible if likes are fully private. This means at least the poster knows who liked their post apart from the liker. Real privacy should be like the upvotes model on Reddit, Hacker News, Tildes, etc. - nobody except the voter (liker) should be able to know.