Fetch Priority provides developers a way to indicate a resource's relative priority to the browser, allowing more control over the order resources are loaded. Many factors influence a resource's priority in browsers. These include type, visibility, and preload status of a resource. This introduces a developer-set "fetchpriority" attribute to HTML elements and a "priority" property to the fetch API allowing developers to influence the computed priority of a resource. Supported fetchpriority values are auto, low, and high.
Explainers: https://github.com/WICG/priority-hints/blob/main/EXPLAINER.md