Querying multiple documents with dereferenced fields in a single query

{
  "error": {
    "description": "expected '}' following object body",
    "end": 65,
    "query": "*[_type in ["banner", "footer"]] { _type == "footer" => { ... } }",
    "start": 40,
    "type": "queryParseError"
  }
}

import { createClient } from "next-sanity";

const sanityClient = createClient({
  dataset: process.env.NEXT_PUBLIC_SANITY_DATASET || "production",
  projectId: process.env.NEXT_PUBLIC_SANITY_PROJECT_ID || "",
  apiVersion: "2021-10-21",
  useCdn: process.env.NODE_ENV === "production",
});

const res = await sanityClient.fetch(`*[_type in ["banner", "footer"]] {
  _type == "footer" => {
    ...
  }
}`);

*[_type == "footer"] {
  ...,
  socials[] {
    ...,
    social->
  }
}

export default {
  name: "footer",
  title: "Footer",
  type: "document",
  fields: [
    {
      name: "title",
      title: "Title",
      type: "string",
    },
    {
      name: "socials",
      title: "Socials",
      type: "array",
      of: [
        {
          name: "social",
          title: "Social",
          type: "reference",
          to: { type: "social" },
        },
      ],
    },
  ],
};

*[_type == "footer"] {
  ...,
  socials[] {
    ...,
    social->
  }
}

*[_type in [ footer, otherDocument ]]

{
  "footer": *[_type =='footer'] {...//whatever fields you need to dereference},
  "otherDocument": *[_type == 'otherDocument']{...//whatever fields you need to dereference}
}