SleepAsync will always fail:

using var sleepCommand = this.CreateCommand(); sleepCommand.SetCommandText("BEGIN sys.DBMS_SESSION.SLEEP(:seconds) END;"); sleepCommand.AddParameter("seconds", sleepTime.TotalSeconds);

should be

using var sleepCommand = this.CreateCommand(); sleepCommand.SetCommandText("BEGIN sys.DBMS_SESSION.SLEEP(:seconds); END;"); sleepCommand.AddParameter("seconds", sleepTime.TotalSeconds);