Issue with Oxxo Pay on PHP 7.4

I have found a critical issue with Oxxo Pay on the servers with PHP 7.4.

When you try to pay the order using that payment method, the field with reference number is empty.

This issue is caused by recent changes made to the PHP 7.4: https://stackoverflow.com/questions/60339183/arrayobject-does-not-work-with-end-in-php-7-4

To solve this issue you need to replace the
$instance = end($instances);
on line 175 in wp-content\plugins\conekta-payment-gateway\lib\conekta-php\lib\Conekta\ConektaResource.php
with

if ($instances instanceof ConektaList and $instances->offsetExists(0)) {
 $instance = $instances->offsetGet(0);
} else {
 $instance = end($instances);
}

Thanks!