Just Output

When you enter the HTML code directly, the layout changes depending on the p and br tags that WordPress automatically inserts.

remove_filter( 'the_content', 'wpautop' ); 

It can be solved by adding the above code.
However, this will disable all auto-inserted p and br tags.
It is not user-friendly.

This plugin can be partially disabled.

Just enter the part you want to disable in the shortcode.

[jo]your HTML code[/jo] 

The author of this plugin loves text editors.