## Problem There are places in the application where `zuora_account_id` is referenced from `Customer` (to be renamed `User`). When the `:account_data_structure` feature flag (introduced in https://gitlab.com/gitlab-org/customers-gitlab-com/-/issues/4794) is enabled, the `Customer`'s associated `BillingAccount` should be used instead. Given the wide usage of this column, we've tackled this as an epic broken down into multiple issues making it easier to iterate. :footprints: Note: The legacy code will be removed in a later iteration once the feature flag has been vetted and promoted in production.