[Bug]: Thumbnails (pdf,mp4) in windows explorer can't be generated

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- [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

Hi,

I found out that in any folders managed by Nextcloud, thumbnails generation for specific files like mp4 and pdf doesn't work.
At the beginning I thought it was Adobe Acrobat or Sumatra PDF's fault, but after some test I realized that the problem happens only in directories managed by Nextcloud.
I have the same problem with MP4, where I use Icaros : thumbnails are generated in any directory but the ones managed by Nextcloud. I don't have the problem with jpg thumbnails
NB : when I installed Nextcloud for the first time all the directories were virtual files, I changed the config and now all the files are stored locally, problem is still there

### Steps to reproduce

1. Open windows Explorer on a directory managed by Nextcloud
2. Open windows Explorer on a directory not managed by Nextcloud
3. Copy a pdf file in both directories
4. Wait for nextcloud to synchronize (optionnal, not sure if it really matter)

### Expected behavior

Compare the result : the thumbnail is generated in the directory NOT managed by Nextcloud, while the thumbnail is not generated in the directory managed by Nextcloud

### Which files are affected by this bug

at least PDF files and MP4

### Operating system

Windows

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

Windows 11

### Package

Appimage

### Nextcloud Server version

Nextcloud Hub 6 (27.1.3)

### Nextcloud Desktop Client version

3.13.0

### 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 Enabled

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

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

### Nextcloud Server logs

_No response_

### Additional info

_No response_