Batch Manufacturing Date

Hello, I want to ask, is the manufacturing date in Batch is automatically inserted for batches that were created from Manufacture? (Have BOM, Work Order, and Stock Entry type is Manufacture)

Please check the code. How to set the manufacturing_date.

So, may I take that since self.manufacturing_date is used, manufacturing_date should be automatically inserted because if manufacturing_date does not have any value, the add_days function cannot run?
I asked what is the default behavior because I need to troubleshoot because in my current setup, the manufacturing date does not show up on batches that was created by manufacture