I have upgraded Magento 2.4.1 to 2.4.2 Special price is showing for a simple product but showing for the configurable product in the category view page.
However, on the product details page, I can see the special price of the configurable product.
Simple Product category view page example.
Configurable product category view example (not showing special price)
Have you tried run php bin/magento indexer:reindex?
Yup - Magento enjoys breaking stuff for us. On the product final_price.phtml template they've got an if statement checking if the page is "listing" page (e.g. a category page, a recently viewed widget, etc) and, if so, do NOT show the original price.
In your module, copy the magento configurable product final_price.phtml file (/vendor/magento/module-configurable-product/view/base/templates/product/price/final_price.phtml) and change the following line:
<?php if (!$block->isProductList() && $block->hasSpecialPrice()) : ?>
to
<?php if ($block->hasSpecialPrice()) : ?>
