Oracle Database 18c is the terminal release for Oracle Streams support. Oracle Streams will be desupported from Oracle Database 19c onwards.
Oracle Streams was deprecated in Oracle Database 12c Release 1 (12.1). It does not support features introduced in Oracle Database 12c and later releases, including the multitenant architecture, the LONG VARCHAR data type, long identifiers, and other features. Oracle GoldenGate is the replication solution for Oracle Database.