Examine source code of med2fed

{
  "manifest_version": 3,
  "name": "med2fed",
  "version": "1.0.2",
  "description": "Redirects Medium.com links to Freedium.cfd",
  "permissions": [
    "tabs",
    "activeTab",
    "scripting"
  ],
  "host_permissions": [
    "*://medium.com/*",
    "*://*.medium.com/*",
    "*://freedium.cfd/*"
  ],
  "commands": {
    "keyboard_redirect": {
      "suggested_key": {
        "default": "Ctrl+Shift+F",
        "mac": "Command+Shift+F",
        "linux": "Ctrl+Shift+F"
      },
      "description": "trigger redirect using keyboard shortcuts"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "action": {
    "default_popup": "popup.html",
    "default_title": "Medium to Freedium Redirector"
  },
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "@med2fed",
      "strict_min_version": "109.0"
    }
  }
}