Just FYI, the Modified by property is available in historical reports, which might be a workaround until Last modified by is a field available in the database directly
It’s also available in the Activity Log, but like reports, it’s not as convenient as having it as a dedicated database field.
I’ve updated the title to make this a suggestion rather than a question. Since the field already exists in multiple places, hopefully, it can be a relatively quick addition if there’s enough demand.