Hi,
this does not seems related to Easy Profile, anyway can you please post me the link of your registration form to check this (read note below)?
or alternatively you can make a simple test to check if it is due to easy Profile, you can disable following plugins from Extensions->Plugins:
- Easy Profile - System Plugin
- Easy Profile - Users Plugin
with these plugins disabled Easy Profile does not do nothing and if the error persists then you are sure that this is not due to our product.

NOTE: now it's 23:24 for us, so probably I will check this tomorrow, so in order to avoid problems with registration of your user then you can enable the captcha tomorrow and reply to this question to notify me to that you are ready to allow me to check it.

Hello
This is not used to unpublish plugins (and problematic on production site) because it's random. People register me with no worries!
If you do not have other customers who make you go back the same problem, it comes from something else.
On the off chance, if you want to try
Regards

Hi,
the error in the screenshot mean that the token used by Google ReCaptcha is not valid (it is expired or already used). ReCaptcha is not a part of Easy Profile, it comes from Joomla.

You may try following solutions:
- Maybe in your site you use different ReCaptcha plugins (Normal and Invisible) in different forms with same key, try to check this or disable one of these plugins
- Try to update Joomla version (maybe there is some update for ReCaptcha plugins)