MySqlConnector: MySqlBulkCopy failed when data is too big (over 80,000 rows)

MySql.Data.MySqlClient.MySqlException (0x80004005): Failed to read the result set.
 ---> System.Net.Sockets.SocketException (10054): An existing connection was forcibly closed by the remote host.
   at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.ThrowException(SocketError error, CancellationToken cancellationToken)
   at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.GetResult(Int16 token)
   at MySqlConnector.Protocol.Serialization.SocketByteHandler.DoWriteBytesAsync(ReadOnlyMemory`1 data) in C:\projects\mysqlconnector\src\MySqlConnector\Protocol\Serialization\SocketByteHandler.cs:line 133
   at MySqlConnector.Protocol.Serialization.ProtocolUtility.<WritePacketAsync>g__WritePacketAsyncAwaited|8_0(ValueTask`1 task_, Byte[] buffer_) in C:\projects\mysqlconnector\src\MySqlConnector\Protocol\Serialization\ProtocolUtility.cs:line 548
   at MySqlConnector.Core.ServerSession.SendReplyAsyncAwaited(ValueTask`1 task) in C:\projects\mysqlconnector\src\MySqlConnector\Core\ServerSession.cs:line 802
   at MySqlConnector.Core.ResultSet.ReadResultSetHeaderAsync(IOBehavior ioBehavior) in C:\projects\mysqlconnector\src\MySqlConnector\Core\ResultSet.cs:line 118
   at MySql.Data.MySqlClient.MySqlDataReader.ActivateResultSet() in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlDataReader.cs:line 130
   at MySql.Data.MySqlClient.MySqlDataReader.CreateAsync(CommandListPosition commandListPosition, ICommandPayloadCreator payloadCreator, IDictionary`2 cachedProcedures, IMySqlCommand command, CommandBehavior behavior, IOBehavior ioBehavior, CancellationToken cancellationToken) in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlDataReader.cs:line 391
   at MySqlConnector.Core.CommandExecutor.ExecuteReaderAsync(IReadOnlyList`1 commands, ICommandPayloadCreator payloadCreator, CommandBehavior behavior, IOBehavior ioBehavior, CancellationToken cancellationToken) in C:\projects\mysqlconnector\src\MySqlConnector\Core\CommandExecutor.cs:line 62
   at MySql.Data.MySqlClient.MySqlCommand.ExecuteNonQueryAsync(IOBehavior ioBehavior, CancellationToken cancellationToken) in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlCommand.cs:line 220
   at MySql.Data.MySqlClient.MySqlBulkLoader.LoadAsync(IOBehavior ioBehavior, CancellationToken cancellationToken) in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlBulkLoader.cs:line 116
   at MySql.Data.MySqlClient.MySqlBulkCopy.WriteToServerAsync(IOBehavior ioBehavior, CancellationToken cancellationToken) in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlBulkCopy.cs:line 167
   at MySql.Data.MySqlClient.MySqlBulkCopy.WriteToServerAsync(IDataReader dataReader, CancellationToken cancellationToken) in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlBulkCopy.cs:line 99
   at KlineImport.Program.Test() in C:\code\quant\KlineImport\Program.cs:line 252
   at KlineImport.Program.Main2(String[] args) in C:\code\quant\KlineImport\Program.cs:line 273

my code:

            using (var conn = await Common.GetDBAsync())
            {
                var kline = new KlineData("usdt_eth", 1, true);

                using (var stream = File.OpenRead(kline.path))
                using (var tx = new StreamReader(stream))
                using (var reader = new CsvHelper.CsvReader(tx, new CsvConfiguration(CultureInfo.InvariantCulture)))
                using (var rd = new CsvDataReader(reader))
                {
                    //var headers = reader.Context.HeaderRecord;

                    var bcp = new MySqlBulkCopy((MySqlConnection)conn)
                    {
                        DestinationTableName = kline.tableName
                    };
                    //Assume the file headers and table fields have the same names
                    //foreach (var header in headers)
                    //{
                    //    bcp.ColumnMappings.Add(header, header);
                    //}

                    //var i = 0;
                    //while (rd.Read())
                    //{
                    //    i++;
                    //}
                    //Log.Information($"{i} line read");

                    await bcp.WriteToServerAsync(rd);
                }
            }

If I uncomment the rd.Read() loop, the log will be read 80473 line read. So the reader is all right. Also I tried removing part of the data from the file and try to find if some ill-formed data cause the error. It turns out the error occurs whenever the file is too big (I guess about 32765), no matter which part of the file is removed.