Error on checkout: Validation message displays immediately

UPDATE 03-31-2021:

We've released updates for our payment extensions to stop these validation errors. Please update to the latest version if your version is lower than:

• Authorize.Net CIM: 4.3.5
• CyberSource: 1.1.1
• First Data/Payeezy: 2.3.7
• Stripe: 2.3.9

Validation error info:

If you experience an error on checkout like:

This credit card type is not allowed for this payment method. Please enter a valid CVV. Invalid credit card expiration date.

This message generally displays in the Discount Code section, but may also be shown at the top or in an alert message on certain custom checkouts. There will also be an associated failed AJAX request, which will show "400 Bad Request".

This validation error is a result of a core bug in Magento 2.3.3+, where payment method validation is fired when the payment method is selected, for the purpose of applying sales promo rules. https://github.com/magento/magento2/issues/28161

At time of writing there is no official solution, and no word on if or when Magento intends to fix the problem properly.