@picadera I have checked your website, and according to your pages source code and the browser console, multiple instances of the same CAPTCHA (with the same key) are loaded.
When you include twice the same form on the same page (once in the body, once in a popup) and the same CAPTCHA is applied on both.
The Google script (CAPTCHA) generates an error and cannot be loaded/submitted:
Uncaught (in promise) Error: reCAPTCHA has already been rendered in this element
at VM32416 recaptcha__en.js:171:238
at HTMLDivElement. (?url=https%3A%2F%2Fpicadera.de&gclid=CjwKCAjw8symBhAqEiwAaTA__C4VmM-qeKKDJTAK8YWQlMO-hBaUXrHsvRdiqMsZ1yECbJ1AjSx6dhoCSPAQAvD_BwE:2646:44)
at Function.each (jquery.min.js?ver=3.6.4:2:3003)
at e..each (jquery.min.js?ver=3.6.4:2:1481)
at onloadSibCallback (?url=https%3A%2F%2Fpicadera.de&gclid=CjwKCAjw8symBhAqEiwAaTA__C4VmM-qeKKDJTAK8YWQlMO-hBaUXrHsvRdiqMsZ1yECbJ1AjSx6dhoCSPAQAvD_BwE:2645:52)
You would need to remove one of the CAPTCHAs,
or use different keys for each CAPTCHA or remove one of the forms.
Best regards,