vmText::sprintf() JROOT/administrator/templates/vmadmin/html/com_virtuemart/product/product_edit_customer.php:72
This line makes eshop dont work in php 8
<input type="text" class="mail-subject input-xxlarge" id="mail-subject" size="100" value="<?php echo vmText::sprintf ('COM_VIRTUEMART_PRODUCT_EMAIL_SHOPPERS_SUBJECT',$this->product->product_name) ?>">