Examine source code of Filter favorites

{
  "manifest_version": 3,
  "name": "Fav-Filter for Vinted",
  "description": "Filter favorite items on Vinted.",
  "version": "1.1.16",
  "icons": {
    "16": "images/icon-16.png",
    "32": "images/icon-32.png",
    "48": "images/icon-48.png",
    "128": "images/icon-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "vintedfavfilteraddonpublic@tobiasfrck"
    }
  },
  "action": {
    "default_icon": {
      "16": "images/icon-16.png",
      "32": "images/icon-32.png",
      "48": "images/icon-48.png",
      "128": "images/icon-128.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.vinted.com/*",
        "*://*.vinted.de/*",
        "*://*.vinted.fr/*",
        "*://*.vinted.it/*",
        "*://*.vinted.es/*",
        "*://*.vinted.lt/*",
        "*://*.vinted.nl/*",
        "*://*.vinted.pl/*",
        "*://*.vinted.pt/*",
        "*://*.vinted.cz/*",
        "*://*.vinted.sk/*",
        "*://*.vinted.ro/*",
        "*://*.vinted.hu/*",
        "*://*.vinted.gr/*",
        "*://*.vinted.fi/*",
        "*://*.vinted.se/*",
        "*://*.vinted.dk/*",
        "*://*.vinted.co.uk/*",
        "*://*.vinted.be/*",
        "*://*.vinted.lu/*",
        "*://*.vinted.at/*",
        "*://*.vinted.hr/*"
      ],
      "js": [
        "main.js"
      ],
      "run_at": "document_end",
      "css": [
        "style.css"
      ]
    }
  ],
  "permissions": [],
  "host_permissions": [
    "*://*.vinted.com/*",
    "*://*.vinted.de/*",
    "*://*.vinted.fr/*",
    "*://*.vinted.it/*",
    "*://*.vinted.es/*",
    "*://*.vinted.lt/*",
    "*://*.vinted.nl/*",
    "*://*.vinted.pl/*",
    "*://*.vinted.pt/*",
    "*://*.vinted.cz/*",
    "*://*.vinted.sk/*",
    "*://*.vinted.ro/*",
    "*://*.vinted.hu/*",
    "*://*.vinted.gr/*",
    "*://*.vinted.fi/*",
    "*://*.vinted.se/*",
    "*://*.vinted.dk/*",
    "*://*.vinted.co.uk/*",
    "*://*.vinted.be/*",
    "*://*.vinted.lu/*",
    "*://*.vinted.at/*",
    "*://*.vinted.hr/*"
  ],
  "background": {
    "service_worker": "background.js",
    "scripts": [
      "background.js"
    ]
  }
}