schlossgespenst Hi
FontAwesome is included in T4 plugin folder - it's on your own server:
ROOT/plugins/system/t4/themes/base/vendors/font-awesome6/
ROOT/plugins/system/t4/themes/base/vendors/font-awesome5/
ROOT/plugins/system/t4/themes/base/vendors/font-awesome/
If you have fontawesome which are loaded remotely from external resource, it must be used in 3rd party extension on your site, kindly check again.