User can't upload to public space (core access token is invalid)

## Describe the bug
A single user can't upload to a shared, public (password-protected) space. There is no user feedback that the upload fails, the progress popup does not open.
The issue only persists in a specific space.

## Steps to reproduce
1. Go to space via link.
2. Try to upload a file.

## Setup

The container is managed via Ansible:

```yml
- name: 🚀 Starts container
community.docker.docker_container:
name: owncloud
image: owncloud/ocis
state: started
restart_policy: unless-stopped
ports:
- " 172.17.0.1:28946:9200"
entrypoint:
- /bin/sh
command: ["-c", "ocis init || true; ocis server"]
env:
OCIS_INSECURE: "false"
OCIS_URL: "https://cloud.catboy.house"
PROXY_HTTP_ADDR: "0.0.0.0:9200"
PROXY_TLS: "false"
OCIS_LOG_LEVEL: "warn"
OCIS_ADD_RUN_SERVICES: "notifications"
NOTIFICATIONS_SMTP_HOST: "{{ smtp_server }}"
NOTIFICATIONS_SMTP_PORT: "{{ smtp_port }}"
NOTIFICATIONS_SMTP_SENDER: "{{ owncloud_smtp_sender }}"
NOTIFICATIONS_SMTP_USERNAME: "{{ owncloud_smtp_user }}"
NOTIFICATIONS_SMTP_PASSWORD: "{{ owncloud_smtp_password }}"
NOTIFICATIONS_SMTP_INSECURE: "false"
user: "{{ owncloud_uid }}:{{ app_gid }}"
volumes:
- "{{ owncloud_volume_config }}:/etc/ocis"
- "{{ owncloud_volume_data }}:/var/lib/ocis"
```

This is the caddy configuration for the site:

```
cloud.catboy.house {
reverse_proxy 172.17.0.1:28946
log {
output file /var/log/caddy/cloud.catboy.house-access.log
}
}⏎
```

The complete setup is here: https://github.com/yuri-becker/catboy-house/tree/main/roles/owncloud

## Additional context
The issue apparently exists using both MS Edge and DuckDuckGo's browser.
I can't reproduce the issue on my end, using the same file.
The file is a PDF of 225KB.
OCIS Version is 6.5.0
Web Client Version is 10.3.0.

The access and OCIS logs are attached (access log was filtered to requests from Edge, ocis log is right after a restart trying to upload the file).

[access.log](https://github.com/user-attachments/files/17228369/access.log)
[owncloud.log](https://github.com/user-attachments/files/17228370/owncloud.log)

Start by comparing the attached access.log and owncloud.log for the failing upload, then inspect the public-space upload and core access-token flow in the OCIS repository. Reproduce with OCIS 6.5.0 and Web Client 10.3.0; done means the affected user can upload to the password-protected public space and receives feedback if the upload fails.

Written by the indexing model from the issue text.