WordPress sends email notifications whenever it automatically updates itself or any of its plugins, themes, or translations. If you want to disable these email notifications, you can use the following code snippets.
// Disable email notification for automatic WordPress core updates
add_filter( 'auto_core_update_send_email', '__return_false' );
// Disable email notification for automatic plugin updates
add_filter( 'auto_plugin_update_send_email', '__return_false' );
// Disable email notification for automatic theme updates
add_filter( 'auto_theme_update_send_email', '__return_false' );