Could app content differ between the device and the provider?¶

Yes. Local cache, drafts and delayed synchronisation can show a different version or state from provider records.

Each source observes a different layer¶

A local message can survive service deletion; a provider may retain delivery events after content disappears; an unsent draft may never reach it. Offline use, backup restoration, editing and account switching create further differences.

Reconcile rather than choose reflexively¶

Preserve both sources and compare message IDs, accounts, sessions, timestamps, edits and deletion events. Ask what each field represents and how synchronisation works. A discrepancy is evidence to explain, not proof that one source is wrong.