@debryc This one is caused by a conflict between the discourse-events plugin (Pavilion’s) and the discourse-calendar (Discourse’s) plugin on your instance. The discourse-calendar plugin gives the class .calendar a set height (645px), and the discourse-events plugin uses that same class in the settings view.
Unless you have specific needs served by the discourse-events plugin (i.e. Pavilion’s) I would suggest you use the discourse-calendar plugin to manage your events and uninstall discourse-events. We actually use discourse-calendar ourselves to manage internal Pavilion events. We only maintain discourse-events for specific use cases we’re supporting, otherwise we’d deprecate it entirely.