Examine source code of Fill it Up!

{
  "manifest_version": 3,
  "name": "Fill it Up!",
  "description": "Automatically fill form fields",
  "version": "0.0.70",
  "minimum_chrome_version": "120",
  "icons": {
    "16": "logo/icon16.png",
    "48": "logo/icon48.png",
    "128": "logo/icon128.png"
  },
  "options_page": "settings/settings.html",
  "action": {
    "default_title": "Fill it Up!",
    "default_popup": "popup/popup.html"
  },
  "permissions": [
    "activeTab",
    "scripting",
    "downloads",
    "contextMenus",
    "storage",
    "userScripts"
  ],
  "optional_permissions": [
    "userScripts"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "css": [
        "fillbutton/fillbuttonmain.css"
      ],
      "js": [
        "settings/mousetrap.min.js",
        "foreground_mainframe.js"
      ],
      "run_at": "document_idle",
      "all_frames": false,
      "world": "ISOLATED"
    },
    {
      "matches": [
        "<all_urls>"
      ],
      "exclude_matches": [
        "*://challenges.cloudflare.com/*",
        "*://service.mtcaptcha.com/*",
        "*://www.google.com/recaptcha/*",
        "*://*.hcaptcha.com/captcha/*"
      ],
      "js": [
        "./settings/common-utils.js",
        "foreground_allframes.js"
      ],
      "run_at": "document_start",
      "all_frames": true,
      "match_about_blank": true,
      "world": "ISOLATED"
    }
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "background": {
    "service_worker": "service-worker.js",
    "scripts": [
      "./settings/common-utils.js",
      "InjectedScripts.js",
      "service-worker.js"
    ]
  },
  "web_accessible_resources": [
    {
      "resources": [
        "fillbutton/fillbuttonshadow.css",
        "InjectedScripts-common.js",
        "ProcessChildSTD.js",
        "ProcessChildGF.js",
        "ProcessChildOF.js",
        "ProcessInputSTD.js",
        "ProcessInputGF.js",
        "ProcessInputOF.js",
        "settings/puphdr.html",
        "fillbutton/*",
        "help/*"
      ],
      "matches": [
        "<all_urls>"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "fillitup.extension@gmail.com",
      "strict_min_version": "136.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}