Hopefully this wouldn’t happen with cloud storage with its extremely high durability rating. You can even protect against “bitrot” yourself with higher end filesystems (ZFS or Btrfs) that do data checksumming and auto healing. Otherwise basic RAID may even help protect against it, although there is some question if the RAID subsystem would detect a random bit flip if not accompanied by a read failure by the hard disk. These reasons are why I’m a big fan of ZFS or Btrfs or cloud storage.
At one point there was some discussion about adding native Parity to Duplicati back end data. See PR #3879, but it has since been closed due to lack of activity.
But if corruption does occur, Duplicati has methods to detect this and recover from it. You may lose the ability to recover some data though. If a dblock becomes unrecoverable then all backup data referencing that block will be affected.