The active thread always in one dataNode,other dataNodes have very few active thread or no active thread

1.Every dataNode has one shard , all the data volume is about 90GB.
2.now my cluster has 5 node ,the master is elected by the ES's election mechanism ,but the result is also same as before , the '_cluster/stats?pretty&human' result:

{
  "_nodes" : {
    "total" : 5,
    "successful" : 5,
    "failed" : 0
  },
  "cluster_name" : "master-cluster",
  "cluster_uuid" : "MH40olNXQkWfCRUi_spkJA",
  "timestamp" : 1646271656813,
  "status" : "green",
  "indices" : {
    "count" : 8,
    "shards" : {
      "total" : 25,
      "primaries" : 20,
      "replication" : 0.25,
      "index" : {
        "shards" : {
          "min" : 2,
          "max" : 5,
          "avg" : 3.125
        },
        "primaries" : {
          "min" : 1,
          "max" : 5,
          "avg" : 2.5
        },
        "replication" : {
          "min" : 0.0,
          "max" : 1.0,
          "avg" : 0.625
        }
      }
    },
    "docs" : {
      "count" : 857997276,
      "deleted" : 4476
    },
    "store" : {
      "size" : "48.7gb",
      "size_in_bytes" : 52326566959
    },
    "fielddata" : {
      "memory_size" : "3.3kb",
      "memory_size_in_bytes" : 3384,
      "evictions" : 0
    },
    "query_cache" : {
      "memory_size" : "62.6mb",
      "memory_size_in_bytes" : 65677952,
      "total_count" : 628200706,
      "hit_count" : 47687,
      "miss_count" : 628153019,
      "cache_size" : 24,
      "cache_count" : 5393,
      "evictions" : 5369
    },
    "completion" : {
      "size" : "0b",
      "size_in_bytes" : 0
    },
    "segments" : {
      "count" : 267,
      "memory" : "171.6mb",
      "memory_in_bytes" : 180011401,
      "terms_memory" : "148.1mb",
      "terms_memory_in_bytes" : 155379717,
      "stored_fields_memory" : "15.5mb",
      "stored_fields_memory_in_bytes" : 16355808,
      "term_vectors_memory" : "0b",
      "term_vectors_memory_in_bytes" : 0,
      "norms_memory" : "1.5kb",
      "norms_memory_in_bytes" : 1536,
      "points_memory" : "7.5mb",
      "points_memory_in_bytes" : 7953472,
      "doc_values_memory" : "313.3kb",
      "doc_values_memory_in_bytes" : 320868,
      "index_writer_memory" : "3.8mb",
      "index_writer_memory_in_bytes" : 4071472,
      "version_map_memory" : "0b",
      "version_map_memory_in_bytes" : 0,
      "fixed_bit_set" : "102.3mb",
      "fixed_bit_set_memory_in_bytes" : 107275864,
      "max_unsafe_auto_id_timestamp" : 1646265608049,
      "file_sizes" : { }
    }
  },
  "nodes" : {
    "count" : {
      "total" : 5,
      "coordinating_only" : 0,
      "data" : 5,
      "ingest" : 5,
      "master" : 5,
      "ml" : 5,
      "voting_only" : 0
    },
    "versions" : [
      "7.5.2"
    ],
    "os" : {
      "available_processors" : 160,
      "allocated_processors" : 160,
      "names" : [
        {
          "name" : "Linux",
          "count" : 5
        }
      ],
      "pretty_names" : [
        {
          "pretty_name" : "CentOS Linux 7 (Core)",
          "count" : 5
        }
      ],
      "mem" : {
        "total" : "313.7gb",
        "total_in_bytes" : 336843325440,
        "free" : "73.7gb",
        "free_in_bytes" : 79195766784,
        "used" : "239.9gb",
        "used_in_bytes" : 257647558656,
        "free_percent" : 24,
        "used_percent" : 76
      }
    },
    "process" : {
      "cpu" : {
        "percent" : 0
      },
      "open_file_descriptors" : {
        "min" : 711,
        "max" : 735,
        "avg" : 717
      }
    },
    "jvm" : {
      "max_uptime" : "19.6h",
      "max_uptime_in_millis" : 70712917,
      "versions" : [
        {
          "version" : "13.0.1",
          "vm_name" : "OpenJDK 64-Bit Server VM",
          "vm_version" : "13.0.1+9",
          "vm_vendor" : "AdoptOpenJDK",
          "bundled_jdk" : true,
          "using_bundled_jdk" : true,
          "count" : 5
        }
      ],
      "mem" : {
        "heap_used" : "61.6gb",
        "heap_used_in_bytes" : 66167834992,
        "heap_max" : "150gb",
        "heap_max_in_bytes" : 161061273600
      },
      "threads" : 1206
    },
    "fs" : {
      "total" : "2.4tb",
      "total_in_bytes" : 2641547755520,
      "free" : "2.3tb",
      "free_in_bytes" : 2574707974144,
      "available" : "2.2tb",
      "available_in_bytes" : 2440406626304
    },
    "plugins" : [ ],
    "network_types" : {
      "transport_types" : {
        "security4" : 5
      },
      "http_types" : {
        "security4" : 5
      }
    },
    "discovery_types" : {
      "zen" : 5
    },
    "packaging_types" : [
      {
        "flavor" : "default",
        "type" : "tar",
        "count" : 5
      }
    ]
  }
}