frontmatter is not found on the collection item

[roma-glushko]

I'm basically trying to add a readingTime value for my blog posts following suggestion from the receipt:
https://docs.astro.build/en/recipes/reading-time/

The new remark plugin was registered:

It's being called when I head to the item view page (verified by console.log() in the plugin).
However, I could retrieve the value to render it on the page. My item element doesn't contain any frontmatter fields:

{
  id: 'slug.mdx',
  slug: 'slug',
  body: 'A lot of text...',
  collection: 'blog',
  data: {
    id: 'abc',
    title: 'Title,
    excerpt: 'Descr',
    keywords: [ 'tag1', 'tag2' ],
    pubDate: 2022-06-06T21:00:00.000Z,
    cover: {
      image: '/blog/slug/hero.jpeg'
    }
  },
  render: [AsyncFunction: render]
}

I'm curios how should I pull that readingTimeMIn value from 🤔