The backup/restore file path is changed between VCF 9.0 and 9.1
Depending on the timing of SFTP backup reconfiguration and VCFA upgrade, the file path may not be aligned between Management and VCFA Appliance
Change the SFTP config in VCF Ops (and then change it back if needed), to get the change to be applied on VCFA.
By reapplying the backup settings, they are pushed out to VCFA as well and backup/restore now works as intended.