An algorithm-downgrade issue was discovered in Couchbase Server before 7.0.4. Analytics Remote Links may temporarily downgrade to non-TLS connection to determine the TLS port number, using SCRAM-SHA instead.
https://www.couchbase.com/alerts
https://forums.couchbase.com/tags/security
https://docs.couchbase.com/server/current/release-notes/relnotes.html