warn Deprecated syntax of sort and/or aggregation field arguments were found in
your query (see https://gatsby.dev/graphql-nested-sort-and-aggregate). Query was
 automatically converted to a new syntax. You should update query in your code.

Current query:

{
  postsRemark: allMarkdownRemark(
    sort: { order: DESC, fields: [frontmatter___dateModified] }
  ) {
    edges {
      node {
        fields {
          slug
        }
        frontmatter {
          category
        }
      }
    }
  }
  categoryGroup: allMarkdownRemark(limit: 2000) {
    group(field: frontmatter___category) {
      fieldValue
      nodes {
        fields {
          slug
        }
      }
    }
  }
}

Converted query:

{
  postsRemark: allMarkdownRemark(sort: {frontmatter: {dateModified: DESC}}) {
    edges {
      node {
        fields {
          slug
        }
        frontmatter {
          category
        }
      }
    }
  }
  categoryGroup: allMarkdownRemark(limit: 2000) {
    group(field: {frontmatter: {category: SELECT}}) {
      fieldValue
      nodes {
        fields {
          slug
        }
      }
    }
  }
}