HX/CNR: Additional Fields Validation ending in PHP Error

In version 20.0 and later if you try to purchase a new domain through client area for a TLD where the registrar is not Hexonet, you will get the following error:

ERROR: Error: Call to undefined function cnic_validateAdditionalFields() in /whmcs/modules/registrars/ispapi/hooks.php:544 Stack trace: #0 [internal function]: WHMCS\\Utility\\SafeInclude::{closure}() #1 /whmcs/vendor/whmcs/whmcs-foundation/lib/Hook/Manager.php(0): call_user_func() #2 /whmcs/vendor/whmcs/whmcs-foundation/lib/Hook/Manager.php(0): WHMCS\\Hook\\Manager->run() #3 /whmcs/vendor/illuminate/support/Facades/Facade.php(261): WHMCS\\Hook\\Manager->validate() #4 /whmcs/includes/functions.php(0): Illuminate\\Support\\Facades\\Facade::__callStatic() #5 /whmcs/cart.php(0): run_validate_hook() #6 {main} {"exception":"[object] (Error(code: 0): Call to undefined function cnic_validateAdditionalFields() at /home/run...', referer: https://domain/cart.php?a=confdomains

As an example .fi TLD is registered through FicoraEPP so it should not have a reason to prompt ispapi to hook the registeration process.

WHMCS Version 8.7.3
PHP Version 8.1
ISPAPI Registrar Module Version 20.0 ->

centralnicgroup-opensource / rtldev-middleware-whmcs

HX/CNR: Additional Fields Validation ending in PHP Error #269