In en-GB.com_virtuemart.sys.ini (admin side) the string is
COM_VM_PRODUCTDETAILS_DISPL_CATS_DESCR=...
and in components/com_virtuemart/views/productdetails/tmpl/default.xml is used
COM_VM_PRODUCTDETAILS_DISPL_CATS_DESC (without "R").
The "R" should be removed from the string in the language file, as all the other strings that describe something end in _DESC (and not _DESCR)