Since reCAPTCHA version 3 is out for time now, this will be a good feature to be introduced to the WHMCS platform. At the same time retains the v2 as well till some time.
This version 3 reCAPTCHA will never interrupt users and is intended to run automatically when users load pages or click buttons. Based on usage, Google will determine if that particular user is a bot. If so – the puzzle challenges will display, stopping the bot in it’s tracks. However, if the user is determined to be human, then the reCAPTCHA requirement will not display. This will ease the "annoyance" of a web user whenever they submit a form, domain search, login, and other usages which enable for reCAPTCHA.
Some of the links about it's feature and advantages,https://www.youtube.com/watch?v=tbvxFW4UJdUhttps://developers.google.com/recaptcha/docs/versions