Perhaps the biggest gotcha was that Googlebot was running Chromium that was years old and required polyfills that you wouldn't otherwise include anymore. Since

Perhaps the biggest gotcha was that Googlebot was running Chromium that was years old and required polyfills that you wouldn't otherwise include anymore. Since May they run a recent Chromium though: "The new evergreen Googlebot" https://news.ycombinator.com/item?id=20482235 https://news.ycombinator.com/item?id=20482235