Calendar 1 Day Events Displaying as 2 Day events

I have an iPhone 16 Plus, recently all of my Canadian Holiday events and Birthday events that are meant to be 1 day events in my calendar have started to display as 2 day events. I’ve tried all the troubleshooting I’ve seen online like refreshing my iCloud and resetting my phone, making sure my time zone is accurate and refreshing that, but regardless of what I’ve tried all of the Holiday events and Birthday events that I can’t manually edit are displayed as two days when they are in-fact only 1 day events.