Plone.formwidget.recaptcha not blocking spam

Hi there. We have a site using Volto 18.32.1 and Plone 6.1.5 where we've added plone.formwidget.recaptcha==3.0.0 so that we can add a captcha to the form block.

However, spam is slipping through, so it is looking like the block is not actually registering the captcha.

Am I missing something in the setup? Is somebody else experiencing the same issue?