Hello Hunter,
welcome to BwPostman!
The message "Check! Do not fill!" and an appropriate input field are a spam trap of the module. The position of this field is absolute top -5000px and should never be visible. But in some cases, some other extensions manipulate such out placed fields although that extension is not responsible for this field. It is a blotchiness of that extension.
I suppose, it is Your Joomla! template, but it could be the template of Virtuemart or Custom Filters Pro or any extension else. To puzzle out, which extension is responsible for the repositioning of "foreign" fields You have to play with the templates and switching off modules and plugins.
As a last resort You could set
#mod_bwpostman .user_hightlight to
display: invisible. But be aware that You at least should use the spam protection of the module. Else You will get lots of useless fake subscriptions. How to override the CSS styles I have described in the
manual
.
Hth
Romana