Personal calendar cannot be removed

Steps to reproduce

1. Go to Calendar App
2. Delete the "Personal" calendar
3. Refresh the view
4. "Personal" calendar appears again

Expected behavior

Once a Calendar is deleted for a user it should not be automatically created again.

Actual behaviour

When the default "Personal" calendar is deleted, it is automatically re-created.

As I cannot define a default calendar other than the personal one, creating a new appointment goes by default to this one instead of the shared one that I want my users to use as default.

Calendar app version

4.7.4

CalDAV-clients used

No response

Browser

Firefox, Chrome, Edge. All latest version

Client operating system

Windows 10

Server operating system

No response

Web server

None

Database engine version

MySQL

PHP engine version

PHP 8.2

Nextcloud version

28.0.5

Updated from an older installed version or fresh install

Updated from an older version

List of activated apps

No response

Nextcloud configuration

No response

Web server error log

No response

Log file

No response

Browser log

No response

Additional info

No response

Start by reproducing the deletion and refresh flow in the Calendar App using the reported Nextcloud 28.0.5 and Calendar 4.7.4 versions, then trace where the Personal calendar is recreated. Done means deleting Personal does not recreate it after refresh and creating an appointment no longer forces that calendar; add or update a regression test if the existing test setup covers this flow.