Lighthouse reports critical requests loaded with a high priority:
See the Lighthouse performance scoring post to learn how your page's overall performance score is calculated.
Lighthouse uses network priority as a proxy for identifying render-blocking critical resources. See Google's Chrome Resource Priorities and Scheduling for more information about how Chrome defines these priorities.
Data on critical request chains, resource sizes, and time spent downloading resources is extracted from the Chrome Remote Debugging Protocol.
Use the critical request chains audit results to target the resources that have the biggest effect on page load first:
async, and so on.
Source code for Minimize critical request depth audit