Oracle GoldenGate Classic Architecture for Oracle database and heterogeneous databases DB2 z/OS, MySQL, SQL Server, and PostgreSQL is deprecated and may be desupported and unavailable in a future release. Oracle recommends using the Oracle GoldenGate Microservices Architecture.
Also,
Classic Extract has been desuported. We no longer can create Classic Extract in OGG 21c. Customers extracting from a ADG instance with classic extract will have to change to downstream capture.
CUSEREXIT for Extract is deprecated and will be desupported in future releases.
The RMTTASK parameter is desupported for Oracle GoldenGate Microservices Architecture. The parameter has been deprecated for Classic Architecture and will be desupported for Classsic Architecture in future releases.
An Oracle Spin by Alex Lima 
hi alex
thank you so much
i have a question
for classic extract on adg i have to change to downstream.
but can i run integrated extract on adg without downstream?
i do that but it is failed and show this error ogg-08221 ora-16000 database or pluggabe database open for read only access.
No you can’t run IE on ADG.