With the latest update of the Astra theme, we have added a spacing around the full width streched layout for elegant looks of the streched layout.

If you are looking to disable the spacing and would like to get the old look of the streched layout, you will need to add the following filter to the function.php file of your child theme.
add_filter( 'astra_stretched_layout_with_spacing', '__return_false' );
This is how it will look after adding the above code to the function.php file of your child theme.

If you are not sure how to add the code to the function.php file, here is an article that will guide you through. If you are not aware what is a child theme and how to install a child them, here is an article that will be helpful.