Empty folders „_Contacts-Backup“ and „_Calendar-Backup“ are created during calendar and contacts Backup

⚠️ Before posting ⚠️

• This is a bug, not a question or an enhancement.
• I've searched for similar issues and didn't find a duplicate.
• I've written a clear and descriptive title for this issue, not just "Bug" or "Crash".
• I agree to follow Nextcloud's Code of Conduct.

Steps to reproduce

1.) Enable Backup of calendar and contacts
2.) Run a Backup

Expected behaviour

Folders should Not be created.

Actual behaviour

The calendar and contacts backup files are correctly stored in the corresponding folder „.Contacts-Backup“ and „.Calendar-Backup“, but the folders mentioned above are created if it‘s not existing.

Android version

14

Device brand and model

Samsung Galaxy A52

Stock or custom OS?

Stock

Nextcloud android app version

3.31.1

Nextcloud server version

31.0.3.2

Using a reverse proxy?

No

Android logs

No response

Server error logs

Additional information

Here is an excerpt of the oc_activity table

from_unixtime(TIMESTAMP);activity_id;subject;subjectparams;FILE
2025-04-17 13:20:46;197808;deleted_self;[{"499943":"/_Contacts-Backup"}];/_Contacts-Backup
2025-04-17 13:48:59;197809;created_self;[{"499973":"/_Calendar-Backup"}];/_Calendar-Backup
2025-04-17 13:49:01;197810;created_self;[{"499974":"/.Calendar-Backup/My calendar_2025-04-17_13-48-57.ics"}];/.Calendar-Backup/My calendar_2025-04-17_13-48-57.ics
2025-04-17 13:49:02;197811;created_self;[{"499975":"/.Calendar-Backup/Feiertage in Deutschland_2025-04-17_13-48-58.ics"}];/.Calendar-Backup/Feiertage in Deutschland_2025-04-17_13-48-58.ics
2025-04-17 13:49:07;197812;created_self;[{"499976":"/.Calendar-Backup/Pers\u00f6nlich_2025-04-17_13-48-59.ics"}];/.Calendar-Backup/Persönlich_2025-04-17_13-48-59.ics
2025-04-17 13:49:08;197813;created_self;[{"499977":"/.Calendar-Backup/Wichtige Daten der Kontakte_2025-04-17_13-49-06.ics"}];/.Calendar-Backup/Wichtige Daten der Kontakte_2025-04-17_13-49-06.ics
2025-04-17 13:49:23;197814;created_self;[{"499978":"/_Contacts-Backup"}];/_Contacts-Backup
2025-04-17 13:49:24;197815;created_self;[{"499979":"/.Contacts-Backup/2025-04-17_13-49-22.vcf"}];/.Contacts-Backup/2025-04-17_13-49-22.vcf

Nel report non sono indicati né un file sorgente né un test. Inizia riproducendo un backup del calendario e dei contatti nell’app Android, quindi traccia il flusso di backup responsabile della creazione delle cartelle; il lavoro è completato quando i file di backup rimangono nelle cartelle corrispondenti con prefisso punto, senza creare le cartelle con prefisso underscore.