“Back in 2012, Reddit experienced a massive outage because of a leap second; the site was inaccessible for 30 to 40 minutes.”
Twenty-seven leap seconds since 1972, and each one breaks somebody. Reddit went down in 2012. Cloudflare’s DNS panicked in 2017 because code assumed time never runs backward. Meta smears the extra second over 17 hours to hide it. The real fix is to stop adding them, and the astronomers can deal with the drift.