So, since you are using strapi.store, please note that its value is stored in DB per environment!
In your case you are using the code from below and you are getting NULL, that means you don’t have the key called plugin_upload_provider in core_store table/collection with environment='production'
An example how strapi.store get values from DB:
You can check in your DB that you have plugin_upload_provider for development env but it’s missing for production.
A solution would be to duplicate the same config row but with a modified environment.