Textblocks are partly underlined

Site URL: http://sei-frei-retreat.de

Hi there, 

Some of the text blocks on my website are completely underlined, although I didn't set it that way. I contacted customer care about this and this is what they said (it's translated form german): 

"I tested the problem on my end and found that the problem was fixed after I disabled scripts in the preview. Here's how to disable scripts on your site:
https://support.squarespace.com/hc/de/articles/205815908#toc-skripts-in-der-vorschau-deaktivieren
Since disabling scripts fixed the issue, the problem is likely caused by custom code added to your site."

I have checked that. I had added something in the custom CSS - but that didn't work anyway because it was related to the front page and that's probably not intended. I deleted everything and the error is still there. Where I disable the scripts on the site I don't understand. But shouldn't be necessary anymore if there is no custom CSS. 

The error is only with some text blocks and does not extend over all blocks of the same font (as you can see on the screenshot below). The font is the Proxima Nova. 

Kind regards
Stella

Can you share link to page where you have problem? I think we can add some simple CSS code to fix this