Discovery source on itom_lu_licensable_cis is not matching with itom_lu_discovery_sources list

For ITOM licensable CIs you see discovery sources-  which are not listed under itom_lu_discovery_sources_list

Any

Working as designed.

OOTB, If a CI is part of "allowable_discovery_source" (i.e. any value from itom_lu_discovery_sources) table and has entry in sys_object_source with the "name" in these "allowable_discovery_source", we consider it as a valid CI to be counted for licensing purpose.
https://<instance>.service-now.com/itom_lu_discovery_sources_list.do

In order to compensate for different CMDB input sources overwriting the discovery_source and last_discovered fields, in practice we measure against the sys_object_source table, via a join using the CI’s sys_id, evaluating the last_scan and name fields of any matching entries.