Long-time visitor Silvano informed me that he was prompted to enter a security code which wasn't visible in the comments section. It turns out that the captcha-less plug-in didn't work as intended, so I had to replace it with a Google recaptcha plug-in. I also noticed that replies to comments weren't possible because I hadn't chosen the "flat" layout instead of the "tree" layout. Since there are several new plug-ins at work on the website I need your feedback in case something doesn't work as planned.
I'm still looking for a survey / form plug-in since the old one which was very easy to set up doesn't work with Joomla 4 or Joomla 5. This website is currently powered by Joomla 4. I'm testing Joomla 5 with my private website www.estelmann.com.