cbbackupmgr backup failed on 7.1.0-1401

Our backup performance runs failed on 7.1.0-1401. The issue is reproducible. The latest good run was running on build 7.1.0-1345.

http://perf.jenkins.couchbase.com/job/rhea-5node2/1490/

Running: ./opt/couchbase/bin/cbbackupmgr backup --archive /workspace/backup --repo default --host http://172.23.97.26 --username Administrator --password password --threads 16 --storage rift

Fatal error: local() encountered an error (return code 1) while executing './opt/couchbase/bin/cbbackupmgr backup --archive /workspace/backup --repo default --host http://172.23.97.26 --username Administrator --password password --threads 16 --storage rift'

From backup-0.log: 

2021-10-03T11:20:59.371-07:00 WARN: (REST) (Attempt 1) (GET) Request to endpoint '/pools/default/buckets/bucket-1/ddocs' failed with status code 400 – logging.(*ToolsCommonLogger).Log() at tools_common.go:28

2021-10-03T11:20:59.371-07:00 (Cmd) Error backing up cluster: failed to execute cluster operations: failed to execute bucket operation for bucket 'bucket-1': failed to transfer index definitions for bucket 'bucket-1': failed to transfer views: failed to get view definitions: failed to execute request: unexpected status code 400 for 'GET' request to '/pools/default/buckets/bucket-1/ddocs', {"error":"no_ddocs_service"}

 
https://s3.amazonaws.com/bugdb/jira/qe/collectinfo-2021-10-04T164633-ns_1%40172.23.97.26.zip
https://s3.amazonaws.com/bugdb/jira/qe/collectinfo-2021-10-04T164633-ns_1%40172.23.97.27.zip
https://s3.amazonaws.com/bugdb/jira/qe/collectinfo-2021-10-04T164633-ns_1%40172.23.97.28.zip
https://s3.amazonaws.com/bugdb/jira/qe/collectinfo-2021-10-04T164633-ns_1%40172.23.97.29.zip