Hi Nathan!
Thanks for getting in touch with us!
By default, past events show a message in the single event page that states that.
In the month view, past events are also shown greyed out, so they differentiate from upcoming events. But, I can see in your site for the month view, that the upcoming events are also grey and it’s hard to tell the difference between past and upcoming.
Having a closer inspection, I can see the grey color is being applied by your theme, so you should check out your theme settings and see if there is any one to select this color.
I hope that helps. Let me know if any follow up question.
Best,
Victor