A problem here is that as the phone restarts after the update, it automatically opens all the apps that were previously opened. The request for permissions is not seen. I rebooted my phone and the problem persists. It is only when I killed all the open apps and opened them individually that the permissions request is seen. This applies to things like the email accounts too as although I had a notification that I had new mail, the app still said that I had no accounts.
Another problem with the Calendar app seen here is that it never stops ‘syncing’. The top bar is continually flashing even though several minutes have elapsed since I requested a ‘sync’. All my calendars are shown however. In case it makes a difference they’re all from a Nextcloud account.
If I go to the Accounts page in Settings and ask there for ‘Update Calendars’ I get an error ‘Server response could not be processed’. The Calendars entry is then greyed out. I’ll look at that after checking the FAQ related to the update.