Unfortunately, I made the mistake of "upgrading" the Reminders app on my new iPhone, and now I can't access my reminders on my Mac until I upgrade to Catalina. That's really lousy. Apparently there's a web interface I can use, but yeah no thanks.
> Upgraded reminders aren't compatible with earlier versions of iOS and macOS. If you upgrade your reminders on your iPhone with iOS 13, your iPad and Mac using the same iCloud account can’t access your reminders until iPadOS and macOS 10.15 Catalina are available. from https://support.apple.com/en-us/HT210220
> Upgraded reminders aren't compatible with earlier versions of iOS and macOS. If you upgrade your reminders on your iPhone with iOS 13, your iPad and Mac using the same iCloud account can’t access your reminders until iPadOS and macOS 10.15 Catalina are available. from https://support.apple.com/en-us/HT210220