X_STORAGE_KEY_UNSHARED
Means
object key is outside every tenant and every shared prefix
Typical cause
a read through /_storage or /media named a key that is not under org/<id>/ and not under a prefix the app listed in defineStorage({ shared }); refused as 404 so the answer never confirms the object exists
Fix
scopedKey(orgId, ...parts) for a tenant's object; for one every reader may have, defineStorage({ disks, shared: { uploads: ['brand/'] } }) with your own disk and prefix