Encountering a phpseclib_mcrypt_filter error while upgrading Magento 2

I’m in the process of upgrading Magento and encountering the following error. I’m unsure how to resolve it. Here’s the error message.

Deprecated: Return type of phpseclib_mcrypt_filter::filter($in, $out,
&$consumed, $closing) should either be compatible with
php_user_filter::filter($in, $out, &$consumed, bool $closing): int, or
the #[ReturnTypeWillChange] attribute should be used to temporarily
suppress the notice in
/home/mindtree/public_html/dev/vendor/phpseclib/mcrypt_compat/lib/mcrypt.php
on line 1107