Extensions Plugin Manager Edit Extension Group
From Joomla! Documentation
Plugins in this group are called after extension install, update or uninstall to manage various extension-related properties.
Extension - Finder
Manage the common words in Smart Search. This plugin has no options.
Extension - Joomla
Manage the update sites for extensions. This plugin has no options.
Extension - Namespace Updater
Build and update the administrator/cache/autoload_psr4.php file that is used to autoload extensions. Warning! This plugin must be enabled as it runs on extension install, update and deletion. This plugin has no options.