Examine source code of Mail in Sync

{
  "manifest_version": 3,
  "name": "Mail in Sync",
  "version": "1.0.0",
  "description": "Quick sync stats and one-click sync for Mail in Sync",
  "icons": {
    "16": "icons/16.png",
    "48": "icons/48.png",
    "128": "icons/128.png"
  },
  "action": {
    "default_popup": "popup.html",
    "default_title": "Mail in Sync",
    "default_icon": {
      "16": "icons/16.png",
      "48": "icons/48.png",
      "128": "icons/128.png"
    }
  },
  "host_permissions": [
    "https://mailinsync.app/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "extension@mailinsync.app",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    },
    "gecko_android": {
      "strict_min_version": "142.0"
    }
  }
}