Seems ineffective and unexpected validation message

Hello,

I am using your plugin successfully on a couple of websites, but on one of them it seems to be ineffective as I receive quite a number of spam messages.
I tried it manually myself and instead of the usual message “please solve…” I get:

“Validation errors occurred. Please confirm the fields and submit it again” (the only field missing or wrong is the unselected V2 captcha)

Of course the submission does not go through and no message is generated, as expected. How come the spammers still go through?

No errors in the logs, nor the browser console.

Using latest CF7, latest WP, your latest version (as for the other websites which work).

Regards