User ID in termbase entry history field seems to be invalid


I'm querying termbase entries through the API. There the createdBy / lastModifiedBy fields seems to contain basic fields of the related user.

However, the id field there seems to be invalid. E.g. the field contains "589481120cf259d01a966ade", but there is no user with that Id (the API returns "User could not be found", and also cannot find it in the WEB UI).

If I navigate in the WEB UI to the user who created this entry, then I see a different ID in the URL.

the ID field here means something else maybe? In case the entry was created/edited by a service user through the API, then all the other fields in createdBy (first name, last name etc) are empty, I only have the ID, and I try to identify the related user based on this.

Can someone help with this?