Core Web Vitals is a relatively new concept introduced by Google in it's search algorithm, which adds a new evaluation criteria to the search ranking. The new Core Web Vitals criteria measure how your web site performs, both load time speeds and the rendering speeds. Drupal has always been a very robust and performant system. There is no surprise that it performs so well with Core Web Vitals, making the rest of the popular CMS chase after it.
The original three Web Core Vitals are:
FID (First Input Delay) - the time that it takes for a browser to start handling an element event after it has been clicked or otherwise interacted with. This is meant to punish those sites that show the content but for some reason become slow or latent, due to large or badly written scripts, or too many intrusive scripts on the page. The punishing threshold is 100ms.
CLS (Cumulative Layout Shift) - the occurrence, when the loaded page starts moving and shifting the layout. This is a very frequent occurrence for the sites where the content "jumps" when the images are being loaded, or some script changes something on the page and it shifts or jumps. The bigger the CLS, the more punishment the search score ratings will receive.
So, now everybody starts optimizing their sites, and that is good - there have been many sites with inhuman blocks and popups that will now be punished. It's great to see that Drupal is in the leaders of this process - has always been. Drupal has always aspired to be robust and user-friendly, and it now shows in SEO search scores.