Bug in page

you mean the backend – and not the frontend.
Guess you have activated the debug mode – in this case there is after the layout input drag&drop window – a window with the generated shortcodes. That is ok. If you do not like to see it – deactivate debug mode.

have a look into your child-theme functions.php if there is a snippet like this:

function builder_set_debug(){
  return 'debug';
}
add_action('avia_builder_mode', 'builder_set_debug');

sorry i’m participant as you are – so no private content for me .
i thought that you concern to the shortcode part – it is the equivalent of your layout above.

or : look to your content if you use f.e. some signs that belongs to a tag f.e. a greater than sign in a table will cause a mismatch.
There are methods to circumvent that.

in connection with Enfold I work exclusively with the Classic Editor – then of course in ALB mode.
I can’t see how the error should have looked like, but I never had problems with the Classic Editor.