Calendar information has disappeared after iOS 26.7 update, please help!

Hey, I updated my iPhone 12 to iOS 26.7, I did this by offloading (not deleting) many apps, including my calendar app. Now all the information I had on my calendar has disappeared, except for a couple of things saved to my gmail/outlook calendars. Its the same across my iPad and my online iCloud Calendar, nothing. I have tried a data recovery from the 12th of Sept 2026, but nothing has reappeared. All toggles of viewing items are green, in the settings-apps-calendar.

Does anyone know why this has happened or how to fix it?