Overriding default sections from new default layout

[X-Tender]

I don't know if I'm right here but...

I use the Builder to setup an Extension to create custom content components.
Now in typo39 the new default content Layout for fluid styled content was introduced:
https://docs.typo3.org/typo3cms/extensions/core/8.7/Changelog/8.6/Feature-79622-NewDefaultLayoutForFluidStyledContent.html

So now every CE is wrapped inside an additional div for example.
But my problem is that when I set a Date on my Custom CE then the new default Template adds an Header.

In the Page linked above it explains how to override Optional Sections (for example the header). But this doesn't work. I just want to tell my CE that doesn't have to render the Header (just like in the example)

So my question is, how can I can achieve this? Is it a missing feature in Builder or somewhere else.