How to delete a calendar event when there is no Delete option?

hi, I can not delete any events on my iPhone's calendar. There is simply no option for Delete.

More background:

• I just updated to iOS 18.0.1
• I had to do a factory reset on my phone since that froze in the middle of it and nearly bricked my phone
• I used the option to reset the phone and restore, which was basically a fresh OS install
• After that completed, I restored from an iCloud backup of my iPad which at least got most of the apps back, but still a ton of re-config to do
• Upon checking the Calendar, I saw to my relief the events are all still there
• However, later in the day, i finished a few things and went to delete them from the Calendar, but there is no option to Delete the event, either if:
  • Holding down on the event and waiting for the menu to pop up
  • tapping on the event and going into it, where you'd normally get a Delete option at the bottom of the event info
• I deleted the Calendar app on my iPhone and reinstalled it. All my events showed up OK, but I still can't delete any
• I was able to delete the event by going into the Calendar on my MacBook Air, but that was more of a test and not an acceptable long-term way to do it
• After all the reconfig, I have everything back to the way it was except Mail did not pick up the settings from the iPad backup so I had to re-add all the config info. That went ok and all mail is working again. (I am pretty sure the Calendar uses my Apple or iCloud ID anyway, but just adding this for cmpleteness.)
• This is a personal phone, so no work Calendar, Mail, MDM/remote mgmt, or anything else.

Any ideas on what might be causing this?