Examine source code of YouTube Subscription Transfer

{
  "manifest_version": 3,
  "name": "Subflow — YouTube Subscription Transfer",
  "short_name": "Subflow",
  "version": "1.3.3",
  "description": "Move any number of YouTube subscriptions between accounts. No API key, paywall, or artificial channel limit.",
  "permissions": [
    "alarms",
    "storage",
    "tabs",
    "unlimitedStorage",
    "scripting"
  ],
  "background": {
    "scripts": [
      "shared/core.js",
      "background/service-worker.js"
    ],
    "type": "classic"
  },
  "action": {
    "default_title": "Open Subflow",
    "default_popup": "popup/index.html",
    "default_icon": {
      "16": "icons/icon-16.png",
      "32": "icons/icon-32.png",
      "48": "icons/icon-48.png",
      "128": "icons/icon-128.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.youtube.com/*",
        "https://youtube.com/*"
      ],
      "js": [
        "content/youtube.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "options_page": "dashboard/index.html",
  "optional_host_permissions": [
    "https://www.youtube.com/*",
    "https://youtube.com/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "subflow@leratojohannesmoselane.github.io",
      "strict_min_version": "142.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}