[Bug]: Error 499 while syncing thousands of new or modified files

### ⚠️ 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've searched 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

From the desktop client I added a local folder for syncing, containing about 50 000 files (photos).

After a few tens of seconds, the client shows a bunch of `[\FilePath] : Network error : 499`, then syncing speed falls to zero.

I can restart the sync : a hundred more files are synchronised before the errors appear again.

### Steps to reproduce

1. From Windows desktop client, add a local folder to sync on server
2. Start syncing
3. Wait for about 100 files to sync and see errors on client.

### Expected behavior

Smooth syncing of thousands of files.

### Which files are affected by this bug

All local files (.jpg) waiting for syncing

### Operating system

Windows

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

Windows 11

### Package

Official Windows MSI

### Nextcloud Server version

30.0.2

### Nextcloud Desktop Client version

3.14.3

### Is this bug present after an update or on a fresh install?

Updated from a minor version (ex. 3.4.2 to 3.4.4)

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

Encryption is Disabled

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

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

### Nextcloud Server logs

Hundreds of `"File" is locked` :

```shell
{"reqId":"l7HW7MVwWoeMkNZ5u5hG","level":3,"time":"2024-11-20T08:34:51+00:00","remoteAddr":"5.48.170.58","user":"vir","app":"no app in context","method":"POST","url":"/remote.php/dav/bulk","message":"\"Photos/2011/photos a reclasser 11642.jpg\" is locked","userAgent":"Mozilla/5.0 (Windows) mirall/3.14.3stable-Win64 (build 20241031) (Nextcloud, windows-10.0.26100 ClientArchitecture: x86_64 OsArchitecture: x86_64)","version":"30.0.2.2","data":{"path":"/Photos/2011/photos a reclasser 11642.jpg"},"id":"673da21c06ae4"}
{"reqId":"l7HW7MVwWoeMkNZ5u5hG","level":3,"time":"2024-11-20T08:34:51+00:00","remoteAddr":"5.48.170.58","user":"vir","app":"no app in context","method":"POST","url":"/remote.php/dav/bulk","message":"\"Photos/2011/photos a reclasser 11641.jpg\" is locked","userAgent":"Mozilla/5.0 (Windows) mirall/3.14.3stable-Win64 (build 20241031) (Nextcloud, windows-10.0.26100 ClientArchitecture: x86_64 OsArchitecture: x86_64)","version":"30.0.2.2","data":{"path":"/Photos/2011/photos a reclasser 11641.jpg"},"id":"673da21c06aed"}
{"reqId":"gyKijf5CLunGJGAZm6po","level":3,"time":"2024-11-20T08:34:51+00:00","remoteAddr":"5.48.170.58","user":"vir","app":"no app in context","method":"POST","url":"/remote.php/dav/bulk","message":"\"Photos/2011/photos a reclasser 11641.jpg\" is locked","userAgent":"Mozilla/5.0 (Windows) mirall/3.14.3stable-Win64 (build 20241031) (Nextcloud, windows-10.0.26100 ClientArchitecture: x86_64 OsArchitecture: x86_64)","version":"30.0.2.2","data":{"path":"/Photos/2011/photos a reclasser 11641.jpg"},"id":"673da21c06af2"}
...
```

### Additional info

Server setup :
* Debian Bookworm
* php-fpm 8.3
* mariadb 11.5.2 (I left the 11.4 LTM version, maybe that was a mistake)

PHP config :

```
upload_max_filesize = 16G
post_max_size = 16G
memory_limit = 16G
max_file_uploads = 100
output_buffering = Off
max_input_time = 3600
max_execution_time = 3600
session.gc_maxlifetime = 3600
default_socket_timeout = 600 # changed from 60 with no change on bug
```

**Edit** : I tried to add `OWNCLOUD_MAX_PARALLEL=1` to the client config file without success.