I have been able to use CommBank(Australia) NFC payments on GrapheneOS ever since I installed it last week (last time I used last night).
I have not changed any settings on my phone, and my bank app did not update overnight.
Today when I tried to pay, the payment machine recognised it as an invalid payment at multiple places. I was not able to get it to work at any of the places, tried updating and restarting app, restarting phone, giving all permissions to CommBank app. None of that changed the issue.
Any ideas what might be happening?

    davlax well your app is definitely communicating over nfc. I don't see a reason for the app to suddenly send invalid card info, so my best guess would be that the transaction is being blocked by your bank.

        vincente213 yeah.. that's what I was thinking as well unfortunately.. Sadly it is the only bank app in Australia that allowed GrapheneOS NFC payments, probably I'll try call them and see if there's a way to get that change revoked, but not a lot of faith on this one.

        Thank you for your response :)

            davlax I wouldn't give up hope quite yet. You don't need them to change their policies, you just need to ask them to reduce fraud detection on your account specifically, which they likely already have a system in place for.

                vincente213 just an update here. I went to the bank and they were able to help me with it. Not exactly sure what they did on their end, but they made some changes, deleted and readded my account in my App and it's all good now :) so no problems here !!