After exploring an alternative payment method, I realized there might be a bug or an issue between GCP and my credit card provider related to the GOOGLE_TEMPORARY payment method, which is meant to verify credit card validity.

To resolve this, go to your Google Cloud Billing page. In the "You have credit..." section, click "Make a payment" and process it manually. This will trigger an automatic withdrawal from your credit card wallet, and your credit will be reflected accordingly.

For example, if you manually pay $500, your credit will show as - $500 instead of simply displaying your available funds +$500. Don't panic—this is just how their UI presents it, even though the balance is correctly applied.