What can be the issue that .NET Framework 4.8 Console app fails to open a connection to Oracle instance when using DB alias only in Release mode. In Debug config app generates the report.
.NET app connection string to DB is
"Data Source=orcl;User Id=MyDB;Password=MyPWD;"
Also have another legacy app that works fine with this connection info.

As soon as I try localhost:1521/orcl.lan as server in Release config, the app generates a report as expected. In Debug config, either server addresses work, localhost:1521/orcl.lan or orcl.

Logon method to Oracle is ported from legacy app and is as following:

private void applyOracleLogon(ReportDocument reportDoc, string dataBaseConnection)
{
    var connectionElements = dataBaseConnection.Split(';');
    string dataSource = connectionElements[0].Replace("Data Source=", "");
    string databaseUser =  connectionElements[1].Replace("User Id=", "");
    string dataBasePassword = connectionElements[2].Replace("Password=", "");
    ConnectionInfo tryInfo;

    foreach(CrystalDecisions.CrystalReports.Engine.Table table in reportDoc.Database.Tables)
    {
        tryInfo = new ConnectionInfo();
        TableLogOnInfo tableLogOnInfo = table.LogOnInfo;
        tryInfo.Attributes = table.LogOnInfo.ConnectionInfo.Attributes;
        tryInfo.Attributes.Collection.Set(DbConnectionAttributes.CONNINFO_DATABASE_DLL, "crdb_oracle.dll");
        tryInfo.Attributes.Collection.Set("QE_DatabaseType", "Oracle Server");
        tryInfo.Attributes.Collection.Set(DbConnectionAttributes.QE_DATABASE_NAME, string.Empty);
        tryInfo.Attributes.Collection.Set(DbConnectionAttributes.QE_SERVER_DESCRIPTION, dataSource);

        tryInfo.LogonProperties.Clear();
        tryInfo.LogonProperties.Add(new NameValuePair2("Server", dataSource));
        tryInfo.LogonProperties.Add(new NameValuePair2("Trusted_Connection", false));

        tryInfo.ServerName = dataSource;
        tryInfo.DatabaseName = string.Empty;
        tryInfo.UserID = databaseUser;
        tryInfo.Password = dataBasePassword;
        tryInfo.IntegratedSecurity = false;

        tableLogOnInfo.ConnectionInfo = tryInfo;
        table.ApplyLogOnInfo(tableLogOnInfo);

        //if (!table.TestConnectivity()) // returns false when in Release and server - orcl
        //{
        //    Console.WriteLine("aaaa");
        //}
    }
}

CR for .NET runtime version – CR 13 SP33. Also have CR 2020 SP4 Patch 4 installed.
As well as latest Oracle Instant Client for 21c for both – 32 and 64 bit.