Weird character displays

There is a strange character that appears on the first date when I add the calendar to a widget (see the right hand column here: https://lorenziniworks.com/dev/contact/). It’s a straight line that extends horizontally.

This appears in multiple browsers, and it has happened the two times I’ve recently used this plugin.

Does anyone know what this could be and how to fix it?

Thanks in advance.

https://www.ads-software.com/extend/plugins/all-in-one-event-calendar/