Commission-free USDC trading via non-USD currencies via Sign In With Coinbase API

At the moment, manually selling USDC to a non-USD fiat currency on the Coinbase website incurs no commission fee as per the Increasing access to USDC internationally: commission-free trading via non-USD currencies article. However, if I attempt to automate this via the Sign In With Coinbase API, it is not commission-free, and this can become very expensive.

This is a major drawback in my opinion as it stifles the adoption and usage of USDC via the Sign In With Coinbase API. In my particular use case, using the Sign In With Coinbase API would incur extra commission fees of more than 50 GBP per transaction, which I would save just by manually carrying out the transaction on the Coinbase website instead, so it is not worth using the Sign In With Coinbase API. Of course, since this is a manual process, it takes more time and increases the chance of user error, but it is still not worth an extra 50 GBP per transaction to automate this via the Sign In With Coinbase API in my particular circumstances.

I originally posted about this, assuming it was a bug, in the Sign In With Coinbase section of the forum, but I have been asked by @Anonymouse to post it here too. Please see my original thread for more details and screenshots.