"Your storage is full [...]"

Nextcloud version: 25.05.7
Operating system and version: Ubuntu Linux 20.04.6
Apache or nginx version: Apache 2.4.41
PHP version: 7.4

The issue you are facing:
When switching to the Files-App in a browser, the message “Your storage is full, files cannot be updated or synced anymore!” appears in the upper right corner.
Image 001

The quota is set to 10 TB for this user
Image 002

The only local disk is ~80 GB of size, with more than 50 % free space. Resizing the disk doesn’t have any effect.
Image 003

Several network shares (on a Windows Server) are mounted via SMB, free disk space on said server is ~1 TB, no other quotas are configured.
Image 004

The files are scanned daily with occ files:scan

Is this the first time you’ve seen this error? (Y/N): N

Steps to replicate it:

  1. Open Nextcloud WebApp and navigate to “Files”

What does your nextcloud.log say? The full explanation will be there.

These are the entries immediately created after login and switching to the “files” app.
loglevel is “Debug”

{"reqId":"p0yUM44hvkfZ7iiZNpgw","level":1,"time":"2023-06-06T13:21:46+00:00","remoteAddr":"[IP]","user":"[Username]","app":"no app in context","method":"GET","url":"/apps/files/","message":"Deprecated event type for \\OCP\\Collaboration\\Resources::loadAdditionalScripts: null","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/113.0","version":"25.0.7.1","data":[]}
{"reqId":"p0yUM44hvkfZ7iiZNpgw","level":1,"time":"2023-06-06T13:21:46+00:00","remoteAddr":"[IP]","user":"[Username]","app":"no app in context","method":"GET","url":"/apps/files/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent is used","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/113.0","version":"25.0.7.1","data":[]}
{"reqId":"V3hB8VotavIB9p8M28nt","level":0,"time":"2023-06-06T13:22:56+00:00","remoteAddr":"[IP]","user":"[Username]","app":"no app in context","method":"GET","url":"/.well-known/webfinger","message":"2 well known handlers registered","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/113.0","version":"25.0.7.1","data":[]}
{"reqId":"vbGlUoieYjuC65hKk7UL","level":0,"time":"2023-06-06T13:22:56+00:00","remoteAddr":"[IP]","user":"[Username]","app":"no app in context","method":"GET","url":"/.well-known/nodeinfo","message":"2 well known handlers registered","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/113.0","version":"25.0.7.1","data":[]}
{"reqId":"CYZnfk3DouCrFesFIqok","level":1,"time":"2023-06-06T13:22:56+00:00","remoteAddr":"[IP]","user":"[Username]","app":"no app in context","method":"GET","url":"/settings/ajax/checksetup","message":"Deprecated event type for OCP\\IDBConnection::CHECK_MISSING_PRIMARY_KEYS: Symfony\\Component\\EventDispatcher\\GenericEvent is used","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/113.0","version":"25.0.7.1","data":[]}
{"reqId":"CYZnfk3DouCrFesFIqok","level":1,"time":"2023-06-06T13:22:57+00:00","remoteAddr":"[IP]","user":"[Username]","app":"no app in context","method":"GET","url":"/settings/ajax/checksetup","message":"Deprecated event type for OCP\\IDBConnection::CHECK_MISSING_INDEXES: Symfony\\Component\\EventDispatcher\\GenericEvent is used","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/113.0","version":"25.0.7.1","data":[]}
{"reqId":"CYZnfk3DouCrFesFIqok","level":1,"time":"2023-06-06T13:22:57+00:00","remoteAddr":"[IP]","user":"[Username]","app":"no app in context","method":"GET","url":"/settings/ajax/checksetup","message":"Deprecated event type for OCP\\IDBConnection::CHECK_MISSING_COLUMNS: Symfony\\Component\\EventDispatcher\\GenericEvent is used","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/113.0","version":"25.0.7.1","data":[]}
{"reqId":"3Cr5cHREAxdeHnoOBq2e","level":1,"time":"2023-06-06T13:25:20+00:00","remoteAddr":"[IP]","user":"[Username]","app":"no app in context","method":"GET","url":"/apps/files/","message":"Deprecated event type for \\OCP\\Collaboration\\Resources::loadAdditionalScripts: null","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/113.0","version":"25.0.7.1","data":[]}
{"reqId":"3Cr5cHREAxdeHnoOBq2e","level":1,"time":"2023-06-06T13:25:20+00:00","remoteAddr":"[IP]","user":"[Username]","app":"no app in context","method":"GET","url":"/apps/files/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent is used","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/113.0","version":"25.0.7.1","data":[]}

Unfortunately none of those log entries are relevant to your issue.

Something is definitely wrong though if the left side panel quota is being reported as 4.4 TB.

Is the underlying OS 32-bit by chance?

it’s 64bit:

root@ubuntu:~# lscpu
Architecture:                    x86_64
CPU op-mode(s):                  32-bit, 64-bit

So where is your datadirectory? Where is the 4.4 TB being stored?

Maybe post the output of of ./occ config:list system too