disabled contact birthdays displayed

Describe the bug

Disabled address books contacts show up in "Contact birthdays" calendar.

To Reproduce
Steps to reproduce the behaviour:

1. Go to /apps/contacts/
2. Create address book
3. Add new contact with birthday, anniversary, etc. to new address book
4. Disable address book
5. Note that new contact is not discoverable in the ui
6. Sync /remote.php/dav/calendars/:user/contact_birthdays/
7. See contact birthday in Contact birthdays calendar

Expected behavior
I would expect disabling an address book hides all data contained within from other applications within nextcloud.

Actual behavior
Tell us what happened instead.

Screenshots
Available upon request.

Server configuration

Operating system: Linux

Web server: Any

Database: Any

PHP version: Several

Nextcloud version: Several

Contacts version: Several

Updated from an older Nextcloud or fresh install: Either

Signing status:

No errors have been found.

List of activated apps:
Available upon request.

Nextcloud configuration:
Available upon request.

Client configuration

Browser: Many

Operating system: All

CardDAV-clients: Multiple

Logs

Web server error log

Available upon request.

Nextcloud log

data/nextcloud.log

Available upon request.

Browser log

Available upon request.

Start at the /remote.php/dav/calendars/:user/contact_birthdays/ endpoint and trace how disabled address books are filtered when contact birthdays are generated. Reproduce the issue with a disabled address book containing a birthday, then verify that its data is absent from the Contact birthdays calendar while enabled address books still appear.