I figured out what was wrong. It was not the timezone of the host system being off, but it was my browser reporting the wrong time. When I opened the console in the browser, and ran Date() the timezone and time I got back was wrong. Turns out Nextcloud relies on the timezone reported by the browser, which makes sense thinking about it.
If anyone else has this problem, a possible cause for your timezone in Firefox being wrong is if you have privacy.resistFingerprinting enabled in about:config.