Files disappear and/or change storage location; massive folder in one storage location

Occasionally files disappear from their original storage location. They are then found either in the folder "deck" or in the "deleted files". Furthermore, Nextcloud created a massive folder in a apparently random storage location with 155.000 files an 42.000 folders, which contains various times specific files as well as former versions of the files. In this folder there is one folder for every user and four more folders with the following names: _groupfolders; adm-230926z5gjgprzsdhpa; appdata_oc0kn00xyu2n; files_external. It contains not only documents of this group folders but of all documents, even not shared documents. In the folder _groupfolder you can find the bug folder again (as it is in file path) and in it all the folders again and so on multiple times. This folder ist located in a group folder. Until now, main problems arine with documents in this group folder.

Anybody an idea if these problems are all related an what the bug could be? I suppose it has something to do with a combination of sharing etc.. Happy for every hint.

Problem is present for all users, idependently of OS, browser, version, devices. Unfortunately I cannot exactly reproduce the issue.

To Reproduce
To reproduce that files are change storage location to deck:

• Create file in group folder
• share the file as attachment in deck
• open attachment
• attachment is opened in deck, not in the originally file path.

I cannot reproduce the creation of the massive folder, as it happens once and now documents are stored multiple times, independently of where they are stored or if they are shared etc.

Client details:

• OS: Windows 10
• Browser: Google Chrome
• Version 130.0.6723.58
• Device: Desktop

Operating system: Windows 10

Web server: nginx

Database: MariaDB

PHP version: 8.2

Signing status: sollte OK sein

Nextcloud version: Nextcloud 28.0.10.1

Where did you install Nextcloud from: https://nextcloud.com/de/install/

Signing status: Managed Nextcloud Business Pro

List of activated apps: Calendar, Collabora Online, Dashboard, Deck, Group folders, Talk with high performance backend, tasks

Start with the reproduction steps involving a file in a group folder, Deck attachments, and opening the attachment; compare the resulting storage path with the original file path. Investigate the reported massive folder and repeated documents alongside the listed Group folders and Deck apps. Done means identifying whether these behaviors share a cause and preventing files from being relocated or duplicated unexpectedly.