This issue has now been resolved upstream at Heroku.
Posted Dec 08, 2021 - 09:59 PST
Monitoring
All of our applications are still up and responding but we're currently unable to deploy any code changes to our platform. We use Heroku (which in turn uses AWS) and they're reporting issues with creating new servers: https://status.heroku.com/incidents/2390.
For our Enterprise customers that use Staging (and have a dedicated instance of ReadMe running) we highly recommend not deploying any new content until this issue has been resolved.