A Director Penalty Notice is the ATO’s way of holding you personally liable for...

https://bizzmarkblog.com/why-missing-the-dpn-deadline-can-make-liability-hard-to-avoid/

A Director Penalty Notice is the ATO’s way of holding you personally liable for company PAYG, GST, and SGC debts. The 21-day clock starts the moment it is issued, so ignore it at your own risk