Hi guys, as Amra said, we are working on a quick version 7.4.2.
As I understand it, this captcha warning shows 5% or 10% of the time.
You saw that everyone will now need a Google "site key" to use the captcha, for each individual site … so the contact form will be disabled by default until it is included in your configuration. A warning will appear on your "store health" if you have not already done so.
Full details to come with the release.