Invoice lines now include the invoice source as a hidden field, making it easier for businesses to customize invoices and show related sale order information when needed. This reduces custom development effort for a common invoicing requirement while keeping the standard invoice view unchanged.

Pad: https://pad.odoo.com/p/r.PE3K5eEMx7gDGarT
Task: https://www.odoo.com/web?#id=21073&view_type=form&model=project.task&menu_id=3942&action=327