Hello,

With Node 16 and when "type": "module" is specified in package.json, the function getFileName() returns the file name with file:// prefix.

Example with the reproducible code below:
$ node index.js

Result:
file:///Users/myuser/projects/myproject/mytest/index.js

Expected result:
/Users/myuser/projects/myproject/mytest/index.js

Reproducible code:
package.json

{
  "name": "mytest",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "callsites": "^4.0.0"
  }
}

index.js

import callsites from 'callsites';

function unicorn() {
	console.log(callsites()[0].getFileName());
}

unicorn();