Shared folder – files reappear after deletion

### ⚠️ Before submitting, please verify the following: ⚠️

- [x] This is a **bug**, not a question or a configuration issue.
- [x] This issue is **not** already reported on Github (I have searched for it).
- [x] Nextcloud Server and Desktop Client are **up to date**. See [Server Maintenance and Release Schedule](https://github.com/nextcloud/server/wiki/Maintenance-and-Release-Schedule) and [Desktop Releases](https://nextcloud.com/install/#install-clients) for supported versions.
- [x] I agree to follow Nextcloud's [Code of Conduct](https://nextcloud.com/contribute/code-of-conduct/)

### Bug description

Nextcloud 34.0.3
Nextcloud Client 34.0.3
PHP v8.3.32
Armbian 26.8.3 bookworm
Apache/2.4.68 (Debian)

Hello,

I’ve encountered the following issue with Nextcloud:

I created a new folder as User A and shared it with User B, granting them full permissions. When I delete a file from the folder as User A, it disappears briefly but then reappears. However, if User B deletes a file, it is correctly removed for both users. What is going wrong here? I suspect the Nextcloud client is causing the issue. If I temporarily disable the client and delete the file as User A via the web browser, the file is gone; however, if I restart the client later, the file reappears.

I have already run `occ files:scan --all` and `php occ preview:cleanup`, removed my User A account from the client, moved the local files to a backup location as a precaution, and completely set up the sync for User A again—all without success.

Based on the two tickets below, I was able to resolve the problem by downgrading to Nextcloud client version 3.16.5, but the underlying issue still needs to be fixed.

https://help.nextcloud.com/t/geteilter-ordner-dateien-werden-nach-loschung-wieder-angezeigt/248938

https://help.nextcloud.com/t/geloschte-dateien-tauchen-standig-wieder-auf/247372

Many users would appreciate a quick solution!

Please let me know if any further details or information are required.

### Steps to reproduce

occ files:scan --all and php occ preview:cleanup without success.
...

### Expected behavior

...

### Which files are affected by this bug

...

### Operating system

Windows

### Which version of the operating system you are running.

Windows 11

### Installation method

Official Windows MSI

### Nextcloud Server version

34.0.3

### Nextcloud Desktop Client version

34.03

### Did this occur after an update or on a clean installation?

Minor version update (i.e. 33.0.0 → 33.0.1)

### Are you using the Nextcloud Server Encryption module?

Yes

### Are you using an external user-backend?

- [ ] Default internal user-backend
- [ ] LDAP or Active Directory
- [ ] SSO - SAML
- [ ] Other

### Nextcloud Server logs

```shell

```

### Additional info

_No response_

Start by reproducing the shared-folder scenario with User A and User B on Nextcloud Desktop Client 34.0.3, noting sync behavior and comparing it with client 3.16.5, where the problem is reportedly absent. The fix is complete when a file deleted by User A remains deleted for both users after synchronization and client restart.

Written by the indexing model from the issue text.