The gerrit change I9a2ebd50, to the CSS which is applied to vector menus with labels (currently only the "variants" menu, from LanguageConverter), do not scale for other similar menus. Anyone wanting to add a new vector menu with a visible title analogous to the "variants" will have to duplicate the CSS because the new CSS is now only for the "#p-variants #mw-vector-current-variant".
I noticed this because the formatting of a menu like that added by one of my user scripts changed after I replaced the h4 by an h3 , and the reason is that this selector doesn't apply to it anymore. Gadgets such as  might have the same kind of problems.
Consider changing the selector to something like
(and updating the code which generates the menu accordingly).