Both Plone 5.2 and Plone 6 have occasional places where <div class="visualClear"><!-- --></div> is scattered in templates, but this looks to be unstyled in either version of Barceloneta.
I ended up having to add this (very narrow) to a site theme (in Plone 5.2) to make a viewlet's display behave:
#viewlet-below-content-body .visualClear {
clear:both;
}
It seems an odd omission that .visualClear is defined in markup, but not styled by default? This is in Sunburst, but never made it to Barceloneta? What's the correct behavior here?