It could be because you’ve entered a grocery name that’s identical to an adverb. The system tries to keep the list of groceries tidy in order not to create duplicates. Meaning chocolate dark and dark chcolate is the same thing, and also that just dark does not make sense. Hene dark would not be allowed as the only word on your grocery list. The system analyses everything entered and tries to detect duplicates, bad grocery names etc. If you think you’ve come across something that is handled wrong by the system, please send a mail to support at groshapp dot com.
See also Why does the system change item names.