Not able to do one time load, from postgres to opensearch using DMS

Trying to migrate existing data from AWS RDS Postgres to AWS managed OpenSearch, but it is not working, no rows were migrated to opensearch, When checking the Cloudwatch log getting below error

Bulk request failed. no retry. TotalRecordCount 4080, FailedRecordCount 4080 [1026400] (elasticsearch_bulk_utils.c:181)

DMS has the following configuration:

{
  "TargetMetadata": {
    "TargetSchema": "",
    "SupportLobs": false,
    "FullLobMode": false,
    "LobChunkSize": 0,
    "LimitedSizeLobMode": false,
    "LobMaxSize": 0,
    "InlineLobMaxSize": 0,
    "LoadMaxFileSize": 0,
    "ParallelLoadThreads": 5,
    "ParallelLoadBufferSize": 100,
    "BatchApplyEnabled": false,
    "TaskRecoveryTableEnabled": false,
    "ParallelLoadQueuesPerThread": 0,
    "ParallelApplyThreads": 0,
    "ParallelApplyBufferSize": 100,
    "ParallelApplyQueuesPerThread": 0
  },
  "FullLoadSettings": {
    "TargetTablePrepMode": "DO_NOTHING",
    "CreatePkAfterFullLoad": false,
    "StopTaskCachedChangesApplied": false,
    "StopTaskCachedChangesNotApplied": false,
    "MaxFullLoadSubTasks": 8,
    "TransactionConsistencyTimeout": 600,
    "CommitRate": 50000
  },
  "Logging": {
    "EnableLogging": true,
    "LogComponents": [
      {
        "Id": "TRANSFORMATION",
        "Severity": "LOGGER_SEVERITY_DEFAULT"
      },
      {
        "Id": "SOURCE_UNLOAD",
        "Severity": "LOGGER_SEVERITY_DEFAULT"
      },
      {
        "Id": "IO",
        "Severity": "LOGGER_SEVERITY_DEFAULT"
      },
      {
        "Id": "TARGET_LOAD",
        "Severity": "LOGGER_SEVERITY_DETAILED_DEBUG"
      },
      {
        "Id": "PERFORMANCE",
        "Severity": "LOGGER_SEVERITY_DEFAULT"
      },
      {
        "Id": "SOURCE_CAPTURE",
        "Severity": "LOGGER_SEVERITY_DEFAULT"
      },
      {
        "Id": "SORTER",
        "Severity": "LOGGER_SEVERITY_DEFAULT"
      },
      {
        "Id": "REST_SERVER",
        "Severity": "LOGGER_SEVERITY_DEFAULT"
      },
      {
        "Id": "VALIDATOR_EXT",
        "Severity": "LOGGER_SEVERITY_DEFAULT"
      },
      {
        "Id": "TARGET_APPLY",
        "Severity": "LOGGER_SEVERITY_DEFAULT"
      },
      {
        "Id": "TASK_MANAGER",
        "Severity": "LOGGER_SEVERITY_DEFAULT"
      },
      {
        "Id": "TABLES_MANAGER",
        "Severity": "LOGGER_SEVERITY_DEFAULT"
      },
      {
        "Id": "METADATA_MANAGER",
        "Severity": "LOGGER_SEVERITY_DEFAULT"
      },
      {
        "Id": "FILE_FACTORY",
        "Severity": "LOGGER_SEVERITY_DEFAULT"
      },
      {
        "Id": "COMMON",
        "Severity": "LOGGER_SEVERITY_DEFAULT"
      },
      {
        "Id": "ADDONS",
        "Severity": "LOGGER_SEVERITY_DEFAULT"
      },
      {
        "Id": "DATA_STRUCTURE",
        "Severity": "LOGGER_SEVERITY_DEFAULT"
      },
      {
        "Id": "COMMUNICATION",
        "Severity": "LOGGER_SEVERITY_DEFAULT"
      },
      {
        "Id": "FILE_TRANSFER",
        "Severity": "LOGGER_SEVERITY_DEFAULT"
      }
    ],
    "CloudWatchLogGroup": null,
    "CloudWatchLogStream": null
  },
  "ControlTablesSettings": {
    "historyTimeslotInMinutes": 5,
    "ControlSchema": "",
    "HistoryTimeslotInMinutes": 5,
    "HistoryTableEnabled": true,
    "SuspendedTablesTableEnabled": false,
    "StatusTableEnabled": true,
    "FullLoadExceptionTableEnabled": false
  },
  "StreamBufferSettings": {
    "StreamBufferCount": 3,
    "StreamBufferSizeInMB": 8,
    "CtrlStreamBufferSizeInMB": 5
  },
  "ChangeProcessingDdlHandlingPolicy": {
    "HandleSourceTableDropped": true,
    "HandleSourceTableTruncated": true,
    "HandleSourceTableAltered": true
  },
  "ErrorBehavior": {
    "DataErrorPolicy": "LOG_ERROR",
    "EventErrorPolicy": null,
    "DataTruncationErrorPolicy": "LOG_ERROR",
    "DataErrorEscalationPolicy": "SUSPEND_TABLE",
    "DataErrorEscalationCount": 0,
    "TableErrorPolicy": "SUSPEND_TABLE",
    "TableErrorEscalationPolicy": "STOP_TASK",
    "TableErrorEscalationCount": 0,
    "RecoverableErrorCount": -1,
    "RecoverableErrorInterval": 5,
    "RecoverableErrorThrottling": true,
    "RecoverableErrorThrottlingMax": 1800,
    "RecoverableErrorStopRetryAfterThrottlingMax": true,
    "ApplyErrorDeletePolicy": "IGNORE_RECORD",
    "ApplyErrorInsertPolicy": "LOG_ERROR",
    "ApplyErrorUpdatePolicy": "LOG_ERROR",
    "ApplyErrorEscalationPolicy": "LOG_ERROR",
    "ApplyErrorEscalationCount": 0,
    "ApplyErrorFailOnTruncationDdl": false,
    "FullLoadIgnoreConflicts": true,
    "FailOnTransactionConsistencyBreached": false,
    "FailOnNoTablesCaptured": true
  },
  "ChangeProcessingTuning": {
    "BatchApplyPreserveTransaction": true,
    "BatchApplyTimeoutMin": 1,
    "BatchApplyTimeoutMax": 30,
    "BatchApplyMemoryLimit": 500,
    "BatchSplitSize": 0,
    "MinTransactionSize": 1000,
    "CommitTimeout": 1,
    "MemoryLimitTotal": 1024,
    "MemoryKeepTime": 60,
    "StatementCacheSize": 50
  },
  "PostProcessingRules": null,
  "CharacterSetSettings": null,
  "LoopbackPreventionSettings": null,
  "BeforeImageSettings": null,
  "FailTaskWhenCleanTaskResourceFailed": false,
  "TTSettings": null
}

Opensearch have index with following settings

{ 
    "settings": {
      "index.max_ngram_diff" :8,
      "analysis": {
        "analyzer": {
          
          "my_ngram_analyzer": {
            "type": "custom",
            "tokenizer": "standard",
            "filter": [
              "lowercase",
              "mynGram"
            ]
          }

        },
        "filter": {
          "mynGram": {
            "type": "nGram",
            "min_gram": 6,
            "max_gram": 14,
            "token_chars": [
                "letter", "digit", "whitespace", "symbol"
              ]
          }
        }
      }, 
        "number_of_shards": 6,
        "number_of_replicas": 1
    },
    "mappings" : {
      "properties" : {
        "created_at" : {
          "type" : "date"
        },
        "id" : {
          "type" : "long"
        },
        "name" : {
          "type" : "text",
          "analyzer":"my_ngram_analyzer"
          , "search_analyzer": "my_ngram_analyzer"
        },
        "phone" : {
          "type" : "text",
          "analyzer":"my_ngram_analyzer"
          , "search_analyzer": "my_ngram_analyzer"
        },
        "updated_at" : {
          "type" : "date"
        }
      }
    }
}

I have tried to insert a sample document using _bulk API on opensearch console and it worked, below is the thing I had tried over opensearch, which worked

POST _bulk
{"index":{"_index":"contacts"}}
{"name": "name","phone" : "11111111","created_at" : "2021-12-21T12:12:59","updated_at" : "2021-12-21T12:12:59","id": 101}