As < and > are special characters in XML, if HTML is used in content e.g. <br> these get loaded in XML as < br >
You will need to convert these special characters back either before storing them or displaying them otherwise your content will look like it is displaying HTML.
WordPress provides a function for this, wp_specialchars_decode() which will convert back the ecoded characters.
If you are using WP ALL IMPORT you can call PHP functions in your templates, an example would be:
For more information about inline PHP functions in WP ALL IMPORT see this guide.