Excessive memory usage

## Describe the bug
I have a personal user space (`ad05fe87-7e1d-4da1-b1e8-cdc93a14003f`) with a size of approximately 100 GB (as shown in the web UI).
However, running `btrfs filesystem du -s ./storage/users/spaces/ad/05fe87-7e1d-4da1-b1e8-cdc93a14003f/` gives
````
Total Exclusive Set shared Filename
453.78GiB 300.00KiB 376.11GiB ./storage/users/spaces/ad/05fe87-7e1d-4da1-b1e8-cdc93a14003f/
````

I already emptied the trash bin and purged revisions using `ocis revisions purge -p /data/storage/users/ --dry-run=false`.

Is there something I am missing or is this a bug?

## Expected behavior
The size reported by the underlying filesystem should match that shown in the web UI.

## Setup
Please describe how you started the server and provide a list of relevant environment variables or configuration files.

OCIS running with `podman`.

Quadlet file:
```console
[Container]
Image=docker.io/owncloud/ocis:7.1

UserNS=auto
User=1000:1000

Network=caddy.network

SecurityLabelLevel=s0:c386,c53,c1022
Mount=type=bind,\
source=./config/,\
destination=/etc/ocis/,\
idmap=uids=@1000-1000-1;gids=@1000-1000-1,\
relabel=private
Mount=type=bind,\
source=/mnt/data0/ocis/,\
destination=/data/,\
idmap=uids=@1000-1000-1;gids=@1000-1000-1

Environment=OCIS_BASE_DATA_PATH=/data
Environment=OCIS_CONFIG_DIR=/etc/ocis
Environment=PROXY_CSP_CONFIG_FILE_LOCATION=/etc/ocis/csp.yaml

Environment=OCIS_LOG_LEVEL=warn
Environment=OCIS_LOG_COLOR=true

Environment=OCIS_URL=[...]
Environment=PROXY_HTTP_ADDR=0.0.0.0:9200
Environment=PROXY_TLS=false
Environment=OCIS_INSECURE=false

Environment=OCIS_EXCLUDE_RUN_SERVICES=idp
Environment=OCIS_OIDC_ISSUER=[...]
Environment=WEB_OIDC_CLIENT_ID=ocis-web
Environment=PROXY_ROLE_ASSIGNMENT_DRIVER=oidc
Environment=PROXY_ROLE_ASSIGNMENT_OIDC_CLAIM=ocis_role
Environment=PROXY_AUTOPROVISION_ACCOUNTS=true
Environment=PROXY_OIDC_REWRITE_WELLKNOWN=true
Environment=OCIS_ADMIN_USER_ID=
Environment=GRAPH_ASSIGN_DEFAULT_USER_ROLE=false
Environment=IDP_ALLOW_DYNAMIC_CLIENT_REGISTRATION=true

Environment=OCIS_SERVICE_ACCOUNT_ID=[...]
Environment=OCIS_SERVICE_ACCOUNT_SECRET=[...]

Environment=OCIS_SHARING_PUBLIC_SHARE_MUST_HAVE_PASSWORD=false
Environment=OCIS_SHARING_PUBLIC_WRITEABLE_SHARE_MUST_HAVE_PASSWORD=true
```