Reminders did not upgrade on my Macbook Air
After i upgraded all my devices, my Reminders on my Macbook Air did not upgrade and are thus no longer synced. What can I do?
If you read the "warning" carefully when you upgraded Reminders on your iOS 13.1 devices, it told you that Macs needed to be upgraded to macOS Catalina to work with them OR you could still access the Reminders, from a pre-Catalina Mac, by logging into your iCloud account and use the Reminders app there.