Yes, frederictardieu. It’s related with authentication data inside your database. You don’t need to drop database in order to resolve this issue, you can just remove record that’s related with your instance.
Also you can finish /uninstall webhook implementation to remove this data automatically. As I know this webhook needs it and will not remove anything without your help. The best way I see is to delete record by “clientKey” in AddonSettings table. You can get it inside your ACE app:
req.context.clientKey