Examine source code of Remove Shorts

{
  "manifest_version": 2,
  "name": "Remove Shorts",
  "version": "1.0",
  "description": "Removes Shorts completely from YouTube subscription feed",
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/feed/subscriptions*"
      ],
      "js": [
        "app.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{b6302e78-fb6f-47db-8fea-c860dc6c8994}"
    }
  }
}