Examine source code of YTM but Better

{
  "update_url" : "https://clients2.google.com/service/update2/crx" ,
  "manifest_version" : 3 ,
  "name" : "YTM but Better",
  "version" : "1.0.3",
  "description" : "YTM but Better — resilient YouTube Music player with synchronized lyrics and visual modes.",
  "permissions" : [],
  "host_permissions" : [
    "https://music.youtube.com/*" ,
    "https://lrclib.net/*" ,
    "https://lyricsplus.prjktla.workers.dev/*" ,
    "https://lyricsplus.atomix.one/*" ,
    "https://lyricsplus.binimum.org/*" ,
    "https://lyricsplus-seven.vercel.app/*" ,
    "https://lyrics-plus-backend.vercel.app/*" ,
    "https://formspree.io/*" 
  ],
  "background" : {
    "service_worker" : "background.js" 
  },
  "action" : {
    "default_title" : "YTM but Better — YouTube Music",
    "default_icon" : {
      "16" : "icon16.png",
      "32" : "icon32.png",
      "48" : "icon48.png",
      "128" : "icon128.png"
    }
  },
  "content_scripts" : [
    {
      "matches" : [
        "https://music.youtube.com/*" 
      ],
      "js" : [
        "content.js" 
      ],
      "css" : [
        "style.css" 
      ],
      "run_at" : "document_idle" 
    }
  ],
  "web_accessible_resources" : [
    {
      "resources" : [
        "rain-window.mp4" ,
        "rain-poster.jpg" ,
        "page-bridge.js" 
      ],
      "matches" : [
        "https://music.youtube.com/*" 
      ]
    }
  ],
  "icons" : {
    "16" : "icon16.png",
    "32" : "icon32.png",
    "48" : "icon48.png",
    "128" : "icon128.png"
  }
}