I've just received email from NAB today:
Thanks for banking with NAB. We’ve recently completed a review of our credit card fees. As a result, from 14 April 2025, the monthly credit card fee on your NAB Rewards Signature Credit Card will increase from $24 per month to $35 per month.
The monthly credit card fee will continue to be reversed if you spend $5,000 or more in a statement period5.
If you’re on a package that has your monthly card fee waived, it will continue to be waived. Fees may incur, when or if, your package ends. Please refer to the Terms and Conditions of your package for full details.