Deprecated APIs are scheduled to be removed from Chrome. Calling these APIs after they're removed causes errors on your site.
How the Lighthouse deprecated API audit fails
Lighthouse flags pages that call deprecated APIs:
Lighthouse includes all deprecated API warnings that Chrome logs to the DevTools Console.
Each Best Practices audit is weighted equally in the Lighthouse Best Practices Score. Learn more in The Best Practices score.
How to remove deprecated APIs
Go to Chrome Platform Status and expand the entries for the APIs that you're using to learn why the APIs are deprecated and how to replace them.