Examine source code of Legacy Verified

{
  "manifest_version": 3,
  "name": "Legacy Verified",
  "version": "1.0.2",
  "description": "Legacy Verified is a browser extension that enables you to view who previously was verified on Twitter",
  "icons": {
    "16": "icons/icon_16.png",
    "32": "icons/icon_32.png",
    "48": "icons/icon_48.png",
    "128": "icons/icon_128.png"
  },
  "action": {
    "default_title": "Legacy Verified Extension",
    "default_popup": "popup.html"
  },
  "permissions": [
    "tabs"
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "/icons/*.png",
        "legacy-verified.csv"
      ],
      "matches": [
        "*://twitter.com/*",
        "*://*.twitter.com/*"
      ]
    }
  ],
  "content_scripts": [
    {
      "matches": [
        "*://twitter.com/*"
      ],
      "run_at": "document_idle",
      "js": [
        "content.js"
      ]
    },
    {
      "matches": [
        "*://*.twitter.com/*"
      ],
      "run_at": "document_idle",
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "legacy-verified@robertspier.nl"
    }
  }
}