Calendar timezone bug

Note this screenshot. It says the appointment is 3 PM, which is untrue. I set it for 2 PM. If I click the appointment, it even agrees I set it for 2 PM, within the same browser tab, on the same computer. It goes from 3 PM to 2 PM when I click it.

This drives me insane. sometimes it’s off by an hour, sometimes 5 hours, and what I don’t get is that this isn’t on different systems, it’s on the same system in the same browser tab.

How can it be 2 PM & 3 PM in the same browser tab? Schrodinger’s nextcloud? I wind up using the titles for all of my times because I can’t trust what I see on the screen.
( default_timezone)

That is set to 'default_timezone' => 'America/Chicago', , but same thing.