Netlify deploys your site under such a URL when you hit "Preview", so you can check the modificatons before you deploy them on your live site. But these preview subdomains are seemingly not deletable (at least that's what I found a few years ago) so it feels like polluting the Internet, as well as leaving draft versions of your content permanently online.
Edit: To correct myself, the docs https://docs.netlify.com/site-deploys/deploy-previews/ do say the URLs of such preview sites are different (they begin with "deploy-preview"), so I'm not sure why the URL of this submission is like that.
Edit: To correct myself, the docs https://docs.netlify.com/site-deploys/deploy-previews/ do say the URLs of such preview sites are different (they begin with "deploy-preview"), so I'm not sure why the URL of this submission is like that.