Commonwealth are charging Coinbase $1.00 to do the 2 transactions verification. The verifications are between 1.01-2.00. Coinbase rejects the $1.00 as below the minimum limit. This is a direct (and effective) tactic from the CBA and Visa to minimise the money going out short term while regulations come and the hope crypto will fall. After spending 2 hours on the phone with CBA they have stated the round fee of $1.00 can't be determined as a credit or debit unless it is approved, though they could confirm that the round figure of 1.00 was rejected by Coinbase.

Coinbase website:

Credit or Debit Card

For cards, these verification amounts will be sent as charges. Coinbase will make two test charges to the card between 1.01 and 1.99 in your local currency. These should appear in the ‘recent activity’ section of your card issuer's website as ‘pending’ or ‘processing’ charges.

Please note: Charges for exactly 1.00 are not used for card verification and can be ignored. These are caused by the card processing network, and are separate from the Coinbase verification amounts.