Examine source code of Festival Countdown

{
  "manifest_version": 3,
  "name": "Festival Countdown",
  "version": "1.0",
  "description": "Live countdown to major cultural festivals worldwide.",
  "action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icon-16.png",
      "48": "icon-48.png",
      "128": "icon-128.png"
    }
  },
  "icons": {
    "16": "icon-16.png",
    "48": "icon-48.png",
    "128": "icon-128.png"
  },
  "host_permissions": [
    "<all_urls>"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "festival-countdown@festiveradar.com",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}