PHP 7.3 reaches end of support in December 2021 and Adobe Commerce 2.3.x reaches end of support in April 2022. You may want to consider planning your upgrade now to Adobe Commerce 2.4.x and PHP 7.4.x to help maintain PCI compliance.
ProductAlert
The Magento_ProductAlert module enables product alerts, which allow customers to sign up for emails about product price or stock status change.