When using the duplicate detection rule, Dynamics 365 users may see different experiences when using the duplicate detection feature from the UI and the Legacy window.
On the Legacy window, when the duplicate detection feature identifies duplicate records, all fields (columns) of the entity are been displayed.
While on the UI window, when the duplicate detection feature identifies duplicate records, only the fields which the rule have been applied on can be seen.
If you come across this experience, do know that this is the current system behavior.
N/B : The name and modified on fields are primary columns which are always going to be displayed when a duplicate detection feature is active.
Also, you can publish only five rules per entity (Account, for example) at a time.
