Ajax not working

Hi there

I use different cf7 forms on my site and since a few days (or recent updates?) ajax is not working anymore. Forms do always refresh the page. Any idea why this happens?

I created a simple test site: https://shorturl.at/kMbHp

But you can also see an implemented form in the product configurator tab called “Spezial”: https://shorturl.at/0UMKf

I checked the theme files like suggested by this article but they seem to be fine, I have those entries: https://contactform7.com/why-isnt-my-ajax-contact-form-working-correctly/

I need this to work again, Could you please help me?

Best reagrds,
Fletsch