Landing page keeps showing "1" at the top

Your software
My Mautic version is: 3.0.2
My PHP version is: 7
My Database type and version is: MYSQL

Your problem
My problem is: There is a “1” always showing up at the top of all my landing page
How do I fix this?

These errors are showing in the log: There are no errors in the log

Steps I have tried to fix the problem:
Switched to code view to see if there is a roaming “1” before tag and tag just before the first visible element but there is none.

Probably it’s in the code.
With the old landing page builder it can happen, that you fill out a content, and then it becomes invisible to the editor, but it shows on the page.