HTTP/2 serves your page's resources faster and with less data moving over the wire.
How the Lighthouse HTTP/2 audit fails
Lighthouse lists all resources not served over HTTP/2:
Lighthouse gathers all resources from the same host as the page and checks the HTTP protocol version of each resource.
Lighthouse doesn't check resources from other hosts because it assumes that you have no control over how third-party resources are served.
Each Best Practices audit is weighted equally in the Lighthouse Best Practices Score. Learn more in The Best Practices score.
How to pass this audit
Serve your resources over HTTP/2.
To learn how to enable HTTP/2 on your servers, see Setting up HTTP/2.