Overview
After a user adds your app to the homescreen, the short_name is the text that
is displayed on the homescreen next to your app icon. In general, it is used
wherever there is insufficient space to display the full name of your app.
Recommendations
Add a short_name property in your Web App Manifest.
{
...
"short_name": "Air Horner",
...
}
Chrome's maximum recommended length is 12 characters.
Check out Manifest Exists for a list of guides that teach you how to properly implement and test "Add to Homescreen" support in your app.
More information
Audit passes if the manifest contains either short_name or name property.
The manifest that Lighthouse fetches is separate from the one that Chrome is
using on the page, which can possibly cause inaccurate results.