"Coupon Free Product" plugin causes Error when creating a New Coupon

-- url of the page with the problem -- : mywebsite.com/administrator/index.php?option=com_hikashop&ctrl=discount
-- HikaShop version -- : 4.6.1
-- Joomla version -- : 4.2.2
-- Error-message(debug-mod must be tuned on) -- : Call to undefined method Joomla\Database\Mysqli\MysqliDriver::query()

Hello, I purchased the Coupon Free Product plugin from your Website.
Unfortunately after activating the plugin, I am unable to create a new Coupon.
When the plugin is activated and I click on Discounts and then "New", the following error occurs:
Une erreur est survenue

0 Call to undefined method Joomla\Database\Mysqli\MysqliDriver::query()

I'm not sure if this is the right place to post this error. If not, please advise the developer or point me in the right direction so they can update the plugin..

thanks,
brett

I went ahead and replaced all instances of $db->query(); with $db->execute(); in the file coupon_free_product.php

This seems to fix the plugin.

I don't know much about PHP but it seems that this method $db->query(); was deprecated back in Joomla 3 and won't work at all on Joomla 4. Seems the developer needs to update his product