when user registration with captcha me then displays the error Could not verify That you are not a robot. (variable K2_COULD_NOT_VERIFY_THAT_YOU_ARE_NOT_A_ROBOT)
The user does not work. The Captcha is set up correctly and works in other places OK
joomla 3.8.13. K2 2.9 page www.eshop-diochi.cz/cs/login/registrace

Captcha returns the timeout-or-duplicate error.If I think correctly, the recaptcha v2 check is online with javascript, and if the form is sent with a button, the check will be rechecked.
Therefore, it is not necessary to call verificationRecaptcha.
In the code is error. This does not allow registration with captcha working.
Also, it is not good that all form fields are checked online, only captcha is checked after the form has been cast.