iPad Calendar not syncing all appointments from iPhone

I have an iPad 9th generation on IOS 18.7.1. It has 64G with 4.5G available. We have an iPhone 13 on IOS 26.5.2 with 128G and 30G available. The calendar on the iPad is not synching fully with the iPhone- not all the appointments are showing that are on the iPhone. I have confirmed that all the calendars are showing and that the appointments in question are on iCloud. We have plenty of iCloud storage available. Both devices are logged into the same iCloud account.

Any idea why appointments are not synching? Thank you.