You notice that the WBS ID of the Work Package is different from the WBS ID seen on the Billing tab.
SAP S/4HANA Cloud
It is the standard behavior of the system.
There can be multiple WBS IDs assigned to one sales item. One WBS is related to the billing item and the other is related to the Work Package. The WBS in the Billing tab is the parent WBS which can have multiple child WBS assigned to it. The WBS in the Work Packages tab is assigned to the WBS in the billing item.
WBS, WBS ID, parent WBS, billing, billing item, work package, project, customer project, cloud, derivation, billing plan , KBA , CA-CPD-SS , S/4HANA Professional Services Cloud - CPM , Problem