In Wikivoyage the heading is substituted by a page banner. This leads to breadcrumbs appearing below the heading as they currently render in the sub heading.
We never resolved this issue in the discussion here: https://en.wikivoyage.org/wiki/Wikivoyage:Travellers%27_pub#Breadcrumb_menu_and_map_icon_dropping_below_the_banner
We could make it possible to configure the extension so that breadcrumbs can be displayed above the heading with a bit of work, but we should work out what the desired behaviour is before pushing ahead with this.
In the interim a user script has been working around this problem.
We'd need to update the Geocrumbs extension so that it can output above the banner. It so happens that the hook that inserts the banner (onBeforePageDisplay) runs after the hook that adds the breadcrumbs (onOutputPageParserOutput).
Currently the hook makes use of sitesubtitle - it would need to be configured to instead to use
to append before the banner.