Excessive storage usage of NextCloud client

### ⚠️ Before posting ⚠️

- [x] This is a **bug**, not a question or an enhancement.
- [x] I've [searched for similar issues](https://github.com/nextcloud/android/issues) and didn't find a duplicate.
- [x] I've written a clear and descriptive title for this issue, not just "Bug" or "Crash".
- [x] I agree to follow Nextcloud's [Code of Conduct](https://nextcloud.com/contribute/code-of-conduct/).

### Steps to reproduce

I am currently facing the issue that NextCloud is 3.6GB in size on my device, though in "On device" there is only 13 MB. Some context
- I recently uploaded a lot of files manually and I think this led to a sudden increase in size.
- I deleted the files manually that were shown in "On device" (when it was several GB), with little effect on the actual used storage
- The android system shows the usage under "User Data", it is therefore not possible to just clean it as cached files from the system settings.

How can we get rid of the files at all? Why are they not counted as "Cache", which would allow their deletion?

UPDATE: the files are still shown in my gallery and apparently stored in /storage/emulated/0/Android/media/com.nextcloud.client/nextcloud/tmp/niels@xyz/upload/location
### Expected behaviour

- Synced/Cached local files should show up in the "Cache" section in android settings
- It should be possible to delete whatever causes this excessive storage usage
- 

### Actual behaviour

Somehow "User data" gets clogged up with large amounts of data (after uploads?)

### Android version

14

### Device brand and model

Pixel 6 Pro

### Stock or custom OS?

Stock

### Nextcloud android app version

3.30.0

### Nextcloud server version

29.0.7

### Using a reverse proxy?

Yes

### Android logs

_No response_

### Server error logs

_No response_

### Additional information

Possible duplicate of #12569