No access to shared birthdays

Debian 11/apache/php 7.4/marinda db/Nextcloud 23/calendar: 3.0.1
I made contacts. I filled birthdays.
Provided access to a specific user and group.
I tried different options.
Birthdays are not available. Users do not see them in the calendar

Bildschirmfoto von 2021-12-03 09-06-47

is the birthday calendar enabled?

Of course allowed