“Heroku has been running a 2nd copy of my scheduler instance since April 6, 2023 and I have zero control over it.”
A deploy on April 6 left an old celerybeat dyno alive with outdated code, so every scheduled task in MusicButler ran twice and thousands of users got duplicate emails. The dyno did not appear in the dashboard. Renaming it in the Procfile was the only way to see it. Support took from April 13 to April 17 to kill it and confirmed there was nothing the customer could have done. Heroku ran a scheduler nobody could see or stop, and the paying customer did the debugging.