iCloud sync related settings are in "Restricted" payload.
There is "Allow iCloud documents and data" in "Restricted" payload.
Or it seems that iCloud for Managed Account setting is also in ABM according to Apple Documents.
Seeing your caputure, I think it may be set in ABM side.
https://support.apple.com/en-mz/guide/apple-business-manager/axm53xk34bq/web
>iCloud Drive: Users can store data in iCloud Drive.
