I received this notification from a non-Synology source, however, it would seem to apply to Cloud Sync/Hyper Backup/etc as well.
From Amazon...
From Amazon...
On August 16, 2019, Duplicati’s integration to the Amazon Drive API will be discontinued. Customers of Amazon storage will continue to have access to their content through our first party applications for Amazon Photos and Amazon Drive. Please make arrangements to discontinue all traffic to the Amazon API before August 16, 2019.