Hi Luicid 
The raw content, which is displayed in the composer, accept an array of HTML tags, thus it will display them in plain text.
If you want to add a line break without using a <br> tag, use \n instead. 
First line\nNew line
If you want to have two paragraphs, you need to add an additional line break:
First line\n\nNew line
Editing these messages won’t show any <br> tag.
Note: paragraphs are created automatically depending on the context when the post is processed, so there’s no need to add these tags to your query raw input.