Index storage size increased a lot after reindex

old index stats
{
  "_shards": {
    "total": 15,
    "successful": 15,
    "failed": 0
  },
  "stats": {
    "uuid": "llYruV2QQvW1aJ3fclAS5Q",
    "primaries": {
      "docs": {
        "count": 4646029,
        "deleted": 0
      },
      "store": {
        "size_in_bytes": 884631128
      },
      "indexing": {
        "index_total": 0,
        "index_time_in_millis": 0,
        "index_current": 0,
        "index_failed": 0,
        "delete_total": 0,
        "delete_time_in_millis": 0,
        "delete_current": 0,
        "noop_update_total": 0,
        "is_throttled": false,
        "throttle_time_in_millis": 0
      },
      "get": {
         removed...
      },
      "search": {
        "open_contexts": 0,
        "query_total": 41278,
        "query_time_in_millis": 43525,
        "query_current": 0,
        "fetch_total": 41130,
        "fetch_time_in_millis": 111370,
        "fetch_current": 0,
        "scroll_total": 8,
        "scroll_time_in_millis": 7318742,
        "scroll_current": 0,
        "suggest_total": 0,
        "suggest_time_in_millis": 0,
        "suggest_current": 0
      },
      "merges": {
        "current": 0,
        "current_docs": 0,
        "current_size_in_bytes": 0,
        "total": 0,
        "total_time_in_millis": 0,
        "total_docs": 0,
        "total_size_in_bytes": 0,
        "total_stopped_time_in_millis": 0,
        "total_throttled_time_in_millis": 0,
        "total_auto_throttle_in_bytes": 104857600
      },
      "refresh": {
        "total": 15,
        "total_time_in_millis": 85,
        "listeners": 0
      },
      "flush": {
        "total": 5,
        "periodic": 0,
        "total_time_in_millis": 85
      },
      "warmer": {
        "current": 0,
        "total": 5,
        "total_time_in_millis": 0
      },
      "query_cache": {
        "memory_size_in_bytes": 0,
        "total_count": 1078,
        "hit_count": 0,
        "miss_count": 1078,
        "cache_size": 0,
        "cache_count": 0,
        "evictions": 0
      },
      "fielddata": {
        "memory_size_in_bytes": 6528,
        "evictions": 0
      },
      "completion": {
        "size_in_bytes": 0
      },
      "segments": {
        "count": 64,
        "memory_in_bytes": 2567293,
        "terms_memory_in_bytes": 1456057,
        "stored_fields_memory_in_bytes": 720872,
        "term_vectors_memory_in_bytes": 0,
        "norms_memory_in_bytes": 20096,
        "points_memory_in_bytes": 222140,
        "doc_values_memory_in_bytes": 148128,
        "index_writer_memory_in_bytes": 0,
        "version_map_memory_in_bytes": 0,
        "fixed_bit_set_memory_in_bytes": 0,
        "max_unsafe_auto_id_timestamp": 1540880597154,
        "file_sizes": {}
      },
      "translog": {
        "operations": 0,
        "size_in_bytes": 1650,
        "uncommitted_operations": 0,
        "uncommitted_size_in_bytes": 1650,
        "earliest_last_modified_age": 0
      },
      "request_cache": {
        "memory_size_in_bytes": 13822,
        "evictions": 0,
        "hit_count": 0,
        "miss_count": 17
      },
      "recovery": {
        "current_as_source": 0,
        "current_as_target": 0,
        "throttle_time_in_millis": 0
      }
    },
    "total": {
      "docs": {
        "count": 13938087,
        "deleted": 0
      },
      "store": {
        "size_in_bytes": 2656471855
      },
      "indexing": { 
          removed...
      },
      "get": {
         removed...
      },
      "search": {
        "open_contexts": 0,
        "query_total": 136385,
        "query_time_in_millis": 151668,
        "query_current": 0,
        "fetch_total": 135952,
        "fetch_time_in_millis": 365018,
        "fetch_current": 0,
        "scroll_total": 25,
        "scroll_time_in_millis": 24113716,
        "scroll_current": 0,
        "suggest_total": 0,
        "suggest_time_in_millis": 0,
        "suggest_current": 0
      },
      "merges": {
        "current": 0,
        "current_docs": 0,
        "current_size_in_bytes": 0,
        "total": 0,
        "total_time_in_millis": 0,
        "total_docs": 0,
        "total_size_in_bytes": 0,
        "total_stopped_time_in_millis": 0,
        "total_throttled_time_in_millis": 0,
        "total_auto_throttle_in_bytes": 314572800
      },
      "refresh": {
        "total": 35,
        "total_time_in_millis": 89,
        "listeners": 0
      },
      "flush": {
        "total": 5,
        "periodic": 0,
        "total_time_in_millis": 85
      },
      "warmer": {
        "current": 0,
        "total": 15,
        "total_time_in_millis": 0
      },
      "query_cache": {
        "memory_size_in_bytes": 0,
        "total_count": 2902,
        "hit_count": 0,
        "miss_count": 2902,
        "cache_size": 0,
        "cache_count": 0,
        "evictions": 0
      },
      "fielddata": {
        "memory_size_in_bytes": 20352,
        "evictions": 0
      },
      "completion": {
        "size_in_bytes": 0
      },
      "segments": {
        "count": 203,
        "memory_in_bytes": 7819733,
        "terms_memory_in_bytes": 4465984,
        "stored_fields_memory_in_bytes": 2161640,
        "term_vectors_memory_in_bytes": 0,
        "norms_memory_in_bytes": 63936,
        "points_memory_in_bytes": 666673,
        "doc_values_memory_in_bytes": 461500,
        "index_writer_memory_in_bytes": 0,
        "version_map_memory_in_bytes": 0,
        "fixed_bit_set_memory_in_bytes": 0,
        "max_unsafe_auto_id_timestamp": 1540880597154,
        "file_sizes": {}
      },
      "translog": {
        "operations": 0,
        "size_in_bytes": 4950,
        "uncommitted_operations": 0,
        "uncommitted_size_in_bytes": 4950,
        "earliest_last_modified_age": 0
      },
      "request_cache": {
        "memory_size_in_bytes": 36555,
        "evictions": 0,
        "hit_count": 0,
        "miss_count": 45
      },
      "recovery": {
        "current_as_source": 0,
        "current_as_target": 0,
        "throttle_time_in_millis": 0
      }
    }
  }
}