Symptoms
ARDocs (e.g. invoice) or order notifcations for the domains subscriptions do not have some information - e.g. End Date (it is set to the same value as Start Date), Duration. Period are empty. The same notifications have this information for the services based on different plans.
Cause
Domain plans are usually configured to take setup and renewal fee. These kind of fees are considered as "one-time" fee and therefore do not have duration or end date.
Resolution
There is a feature request with id #PFR-1280 ("Consider setup and renewal fee for domains as charges for subscription period not as one-time charges") to change the approach. The related duplicate feature requests ids are #PBA-42230 ("Period in notifications not showing for domain subscriptions") and #PBA-49313("Consider setup and renewal fee for domains as charges for subscription period not as one-time charges").