With the new PSR-16 compatible caching engine we introduced recently, the new way to get the caching object is with something like this sample code

cacheOnSugar.php

<?php

// remember to set redis on config_override.php
/*
$sugar_config['external_cache_disabled'] = false;
$sugar_config['external_cache_disabled_redis'] = false;
$sugar_config['external_cache']['redis']['host'] = 'sugar-redis';
*/

// to test the simplest standalone script
/*
define('sugarEntry', true);
require_once('include/entryPoint.php');
$GLOBALS['current_user'] = BeanFactory::newBean('Users')->getSystemUser();
*/

use Sugarcrm\Sugarcrm\DependencyInjection\Container;
use Psr\SimpleCache\CacheInterface;

$cache = Container::getInstance()->get(CacheInterface::class);

$cacheVariableKey = 'unique_cache_key';
$optionalTTL = 30;
$storedVariable = $cache->get($cacheVariableKey);

// return cached info
if (isset($storedVariable)) {
    $decodedStoredVariable = json_decode(base64_decode($storedVariable), true);
    $GLOBALS['log']->fatal('returning value of key ' . $cacheVariableKey . ' from cache ' . print_r($decodedStoredVariable, true));
    return $decodedStoredVariable;
} else {
    // retrieve the actual live data here
    $data = ['a', 'b', 'c'];

    $GLOBALS['log']->fatal('retrieving live data and storing it into ' . $cacheVariableKey);

    // store retrieved data in cache and return
    $cache->set($cacheVariableKey, base64_encode(json_encode($data)), $optionalTTL);
    return $data;
}

// to delete previously cached data use
//$cache->delete($cacheVariableKey);