In a Record Producer, there is one form field: "Category" which would be considered as the category under which the record producer comes in while searching on Service Portal.
i.e. Category :
The service catalog category this record producer belongs to. When users perform catalog searches, only items that are assigned to a category appear in search results.
Please refer to below product documentation for the same:
The categories defined in the "Categories" related list of a Record Producer won't be considered as a category of that record producer during the search.
But , if we explore the categories on the portal, then the record producer would be shown under the category which is part of Categories related list.