Fully agreeing with this request, as I also wondered, if it was somehow possible to make a clear distinction "at one glance" without opening the calendar events' details.

For us, it is an essential function that when you look at your own calendar, you can see at a glance whether it is a confirmed appointment or an appointment with reservations. Or whether it's an appointment away from home or in the office. A diagonally striped background would be possible for appointments with reservations, for example.