Apps using free dynos will be automatically converted to Eco dynos and scaled down to 0 starting November 28, 2022. You can't scale them up from 0 until you subscribe to the Eco dynos plan or upgrade to another paid tier. The apps will remain and their paid add-ons will not be affected.
Learn more about our Eco dynos plan here.
See our blog post and the Removal of Heroku Free Product Plans FAQ for more info related to the ending of free plans.