The Fulfillment API was deprecated in the Shopify 2022-07 release. However the cancel endpoint was missed and this change rectifies that mistake.
Apps will have until the 2023-04 release to migrate away from the deprecated API and use Fulfillment Orders instead. To help you seamlessly migrate, we’ve crafted a migration guide that walks you through the process of moving to Fulfillment Orders. To learn more, visit the migration guide on Shopify.dev.