Sending a revalidation request once a Firebase Realtime database has been changed

Question

So, recently I have been dealing with making a blog website where the user can both read everything I want to tell them in the text and leave a comment so that I can know their opinion. I use markdown files to make the blog like that:

export async function getStaticProps({ params: { postname } }) {
  const fileName = readFileSync(`posts/${postname}.md`, 'utf-8')
  const { data: frontmatter, content } = matter(fileName)
  const snapshot = await retrieveComments(postname).then(snapshot => {
    return { props: { snapshot } }
  })
  const slug = postname

  return {
    props: {
    frontmatter,
    content,
    snapshot,
    slug
  }
 }
}

Before that I get the paths:

export async function getStaticPaths() {
  const files = readdirSync('posts')

  const paths = files.map(fileName => ({
  params: {
    postname: fileName.replace('.md', '')
  }
 }))

 return {
   paths,
   fallback: false
 }
}

Well, as you can see, I retrieve the markdown data, work with it and get the snapshot of the list of the comments in the database in getStaticProps. The problem is that the list of comments never changes its value in the production version, which happens because I get the static props. So I have found out that I can revalidate the props. How do I send the request that the props need to be revalidated when a new comment is added? Obviously, adding a new comment means changing the database, so I think we can sort of wait for a change in the database.

In api/revalidate.js I have this:

export default async function handler(req, res) {
  try {
    await res.revalidate(req.query.path);
    return res.json({
      revalidated: true
    })
  } catch (err) {
    return res.status(500).send('Error revalidating');
  }
}

Also, I use Vercel as my hosting.