Examine source code of QualityTube

{
  "manifest_version": 3,
  "name": "QualityTube",
  "version": "1.0.5",
  "description": "Automatically set YouTube videos to the highest available quality",
  "browser_specific_settings": {
    "gecko": {
      "id": "youtube-auto-quality@gauravpatidar.dev",
      "strict_min_version": "128.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "host_permissions": [
    "https://www.youtube.com/*",
    "https://youtube.com/*"
  ],
  "permissions": [
    "storage"
  ],
  "action": {
    "default_popup": "popup.html",
    "default_title": "QualityTube"
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.youtube.com/*",
        "https://youtube.com/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end"
    }
  ],
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  }
}