Examine source code of Volume Booster

{
  "manifest_version": 3,
  "name": "Volume Booster",
  "version": "1.2",
  "description": "Boost audio volume up to 650% on any webpage",
  "permissions": [
    "activeTab",
    "storage",
    "scripting"
  ],
  "action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icons/icon16.png",
      "48": "icons/icon48.png",
      "128": "icons/icon128.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start",
      "all_frames": true
    }
  ],
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "volume-booster@22291111.xyz",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "collects_personal_data": false,
        "collects_location_data": false,
        "collects_health_data": false,
        "collects_financial_data": false,
        "collects_authentication_info": false,
        "collects_user_activity": false,
        "collects_website_content": false
      }
    }
  }
}