In pre-16.0 databases, REMOTE DBA authority allowed a user to perform replication and synchronization operations using dbremote and dbmlsync.
The REMOTE DBA authority has been replaced by the SYS_RUN_REPLICATION_ROLE system role. Change your applications to grant this role, instead of REMOTE DBA.
The GRANT REMOTE DBA statement syntax is still supported but deprecated. Another replication-related role has also been introduced: the SYS_REPLICATION_ADMIN_ROLE system role. This role allows user to administer replication.