Appointments on iCal on my iMac 24" gone after updating to iOS 26.2

When I opened my Calendar today all my past and future appointments were gone. I recently updated to Tahoe 26.2 on my iMac 24". Yesterday the calendar was as it has been. Today, everything is gone. I don't backup to iCloud. What is going on with this new iOS? Is there any way I can get those appointments back?

I have most of my appointments on my iPhone 15. Is there a way to copy that Calendar to the iMac Calendar without using iCloud?