Substack! They were down - again - a couple days ago, and the message was:
> You've requested a page on a website (substack.herokuapp.com) that is on the Cloudflare network. Cloudflare is currently unable to resolve your requested ___domain (substack.herokuapp.com).
Who in 2022 is actually using Heroku at serious scale? This is a dying service, no one sane want to bet on that.