Hi,

As I see, this line caused by an ads from you auto place on that space - check this image: https://prnt.sc/r0lnbl

You can try add more this code to Customize > Custom CSS to remove it:

#respond h3.comment-reply-title span.ezoic-adpicker-ad:before,
#respond h3.comment-reply-title span.ezoic-adpicker-ad:after{ content: none; display: none; }

Best Regards,

PenciDesign