Get scheme from URI in Drupal 9

getscheme.php

<?php

$uri = 'public://path/to/file.txt';
/** @var \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface $stream_wrapper_manager */
$stream_wrapper_manager = \Drupal::service('stream_wrapper_manager');
$scheme = $stream_wrapper_manager->getScheme($uri);
// $scheme = 'public';