Hi,
The plugin uses ReCaptcha V2.
ReCaptcha V2 and V3 are for different use cases.
The ReCaptcha V2's goal is to be added to forms and get a "human" or "bot", yes / no answer from ReCaptcha in order to procees the form or not.
The ReCaptcha V3 doesn't return a yes / no but a score based on the probability it thinks the current user is a bot or a human. It can be placed on links / buttons to register the actions of the user on a website. So the V3 doesn't have a captcha to be solved. It basically works like the invisible mode of V2, but without a fallback to a normal captcha when it thinks the user is a bot or it doesn't know.
Captcha can be bypassed. Developping a captcha plugin based on ReCaptcha v3 could be done, but I don't think it would help much with your spam accounts issue.
I would rather recommend you use this extension:
extensions.joomla.org/extension/ospam-a-not/
The concept is completely different and so far it seems to work great in order to stop spam registrations.