ReCaptcha after try to make an entrance

The ReCaptcha button as Spam-Protection rotates indefinitely after entering a guestbook entry and therefore you cannot make an entry. The keys for the website and the secure key have been correctly determined and entered in the guestbook component. In the Joomla 3 System Configuration, the ReCaptcha 2 was also activated as Spamprotection. In the corresponding plugin the same keys were also entered and the plugin was activated. What to do? Please help me.

Here is the problem:
https://im-ericbaader.de/deine-erinnerungen-sind-gefragt.html

Try to make an entrance there - it will not work ...