Database.*Async() Operations Fail with UnsupportedOperationException on Salesforce Connect: OData 4.01 External Objects

When using Salesforce Connect: OData 4.01 as an External Data Source, Apex DML operations using Database.*Async() methods (updateAsync, insertAsync, deleteAsync, upsertAsync) will fail with.

Error ID: XXXXX-XXXX (1704338935)

This is commonly seen after migrating from OData 2.0 to OData 4.01, as these methods were supported under the OData 2.0 adapter.

The OData 4.01 adapter requires an active, live connection for the entire duration of a write operation and does not support "disconnected row creation" — the pattern Database.*Async() methods they rely on.

This behavior is Working as Designed (WAD).