The customer observed that putting some specific formatting inside custom style breaks preview after publishing.

Steps to reproduce:
1. Add a custom style and name it test_custom_style.

ezpublish:
    ezrichtext:
        custom_styles:
            test_custom_style:
                template: 'ezrichtext/test_custom_style.html.twig'
            inline: false

2. Create test_custom_style.html.twig file and place it in app/Resources/views/ezrichtext directory and put the following code there:

<div>{{ content|raw }}</div> 

3. Create new content and use the newly created custom style.

4. Put some italic/bold text, use Shift+Enter (soft break) and add some more text, like follows:

test
test2

5. Publish the article.

Result:

All the text after the soft return is cut out. Also, the formatting of the first word is missing. You will be presented with just "text" both in the content preview and in the front SiteAccess.