X_REPLICATION_FAILED
Means
the replication connection was refused
Typical cause
wal_level not logical, a role that may not create or extend the publication (the replicator ensures it at boot), a role without REPLICATION, a slot another replicator holds, wrong credentials
Fix
the message names the object; the fix is the exact setting, CREATE PUBLICATION or pg_drop_replication_slot statement — and a REPLICATION grant only on a cluster dedicated to the app (why)