We are using the HubSpot API and have made our own implementation of Googles ReCaptcha. We are validating before sending the form data via the API to HubSpot, and it has worked fine since November/December last year. We have used the captcha switch on the HubSpot form (Options > Display Captcha on this form?) on our side to decide which forms to add the captcha.
But now we see that when that switch is on, HubSpot is now rejecting the posted data. The response is an html page with a message saying something about invalid captcha. And, as far as we see, the posted data are lost.
We will handle this by always have the HubSpot form captcha switched off (and verify that it actually is, before showing the form). But because we may have lost important data here, we are very interested in knowing when this "feature" was introduced. For, as far as we can see, this has changed recently. And maybe this have affected other clients too. :-/