new PerformanceObserver((list) => {
  list.getEntries().forEach(console.log);
}).observe({ type: 'paint', buffered: true });

performance.getEntriesByType('paint').forEach(console.log);

These two snippets log matching paint entries in Chrome, Firefox, Edge, and Opera. However, in Safari 15.3 the PerformanceObserver approach doesn't log at all (the callback isn't invoked), but the getEntriesByType approach does log the "first-contentful-paint" entry. It seems that Safari supports PerformanceObserver.observe and supports the PerformancePaintTiming API. Why does the above PerformanceObserver approach not work in Safari?

If there is a bug in Safari do you think that getEntriesByTypes without a PerformanceObserver's buffer is OK to use instead? Thanks.