WYSIWYG adds line break to list element

Hi,

I added a wysiwyg field in my block.

[
   'name'              => __( 'Text', 'custom-blocks' ),
   'id'                => $prefix . 'teaser-textarea',
   'type'              => 'wysiwyg',
   'options' => [
	'textarea_rows' => 5,				
   ],
],

Adding list elements in this field outputs something like this:

<ul>
  <li>...</li>
  <br>
  <li>...</li>
  <br>
</ul>

How to prevent these line breaks?
Are there any special configurations?

The preview and code in the TinyMCE Editor looks good, but not in the Gutenberg Editor (lefthand).

Thanks!