not possible to change settings of SHARED calendars

Steps to reproduce

1. create or open exisiting calendar in Nextcloud calendar app
2. share the calendar with admin or team members
3. as soon as the calendar is shared, it is not possible to edit the settings of the calendar again
4. it is also not possible to unshare, export or delete the calendar
5. the only option is for "calendars WITH tasks" to delete them at the tasks app.

Expected behavior

the shared calendar should be work as usual. Settings should be possible to be maintained. It should be possible to unshare, export or even delete the calendar.

It should be possible to add shared calendars by the person that I have shared the calendar with, without my password. That's not possible anymore. Now I have to open my calendar with MY password at their device as work around.

Actual behavior

just opening the settings of a shared calendar, the window closes after 4 seconds and either restarts or I have to login again. This doesn't happen with calendars that have not been shared. The issue occurs inside Nextcloud, also while Thunderbird or DAVx5 are not active.

Calendar app version

5.1.2

CalDAV-clients used

Thunderbird (Betterbird), DAVx5

Browser

Firefox 136.0

Client operating system

Windows 11

Server operating system

Asustor Flashstor FS6712X

Web server

None

Database engine version

None

PHP engine version

None

Nextcloud version

No response

Updated from an older installed version or fresh install

None

List of activated apps

Nextcloud configuration

Web server error log

Log file

Browser log

Additional info

No response

No source file, test, or Nextcloud version is identified. Reproduce the issue in Calendar app 5.1.2 with a shared calendar, then trace the settings and sharing flow; done means shared calendars can be edited, unshared, exported, and deleted without the window closing or requiring another login.