I think I found a bug in the calender app:
I’m on Fairphone 4, official A14 and Version 3.4. When I switch to the list-view in calender (where all entries are shown in chronological order), go back to month view and then tap on a day in the month-view, it won’t show me the day to create an entry but instead the list view of all entries again. This will only stop when I switch to day-view first and then to month-view again.