Hello,
I am on php: 8.0.27, but I don’t think this is the problem.
You used a plugin that comes with woocommerce and put some extra code in it.
Now woocommerce has updated this plugin, but you still use the old template quantity-input.php (I think 🙂
There is also a quantity-input.php in the woocommerce template map:
* Product quantity inputs
*
* This template can be overridden by copying it to yourtheme/woocommerce/global/quantity-input.php.
*
* HOWEVER, on occasion WooCommerce will need to update template files and you
* (the theme developer) will need to copy the new files to your theme to
* maintain compatibility. We try to do this as little as possible, but it does
* happen. When this occurs the version of the template file will be bumped and
* the readme will list any important changes.
*
* @see https://docs.woocommerce.com/document/template-structure/
* @package WooCommerce\Templates
* @version 7.2.1
*/