I can't get metafield data through storefront API

[TinWinston]

I can get metafield data through the restadmin API，The returned results are as follows:

But I can't get metafield data through storefront API:

 $query = <<<QUERY
  query {
    customer(customerAccessToken: "$token") {
      id
      createdAt
      metafield(namespace: "custom", key: "avtar"){
        value
      }
      firstName
      lastName
      acceptsMarketing
      email
      phone
    }
  }
QUERY;
        $resp = $clientFront->query(["query" => $query])->getDecodedBody();

The resulting metafield result is null：

["data"] => array(1) {
    ["customer"] => array(8) {
      ["id"] => string(48) "Z2lkOi8vc2hvcGlmeS9DdXN0b21lci82MzI1NTI3NjQyMzY4"
      ["createdAt"] => string(20) "2022-09-02T02:39:38Z"
      ["metafield"] => NULL
      ["firstName"] => string(7) "Chunhui"
      ["lastName"] => string(3) "Ren"
      ["acceptsMarketing"] => bool(false)
      ["email"] => string(24) "renchunhui2008@gmail.com"
      ["phone"] => NULL
    }
  }

[TinWinston · Accepted solution]

If it needs to be selected in the background Expose this metafield to Storefront API requests.