Heroku Postgres or Heroku Data for Redis instances provisioned with the hobby-dev plan will be marked for deletion starting November 28, 2022, regardless of the dyno plans used for the application that they're attached to. Instructions can be found in our Dev Center for upgrading Heroku Postgres and Heroku Data for Redis.
You can download your Heroku Postgres data if you need a backup.
To recover you data, contact Heroku Support as soon as possible.
See our blog post and the Removal of Heroku Free Product Plans FAQ for more info related to the ending of free plans.