Can I backup iCloud using mobile data?
Can I update iCloud using mobile data?
Question marked as
With a 5G-capable iPhone or 5G-capable iPad, and a 5G cellular plan, and a 5G connection, usually yes.
Also possible using a carrier-provided MiFi or Jetpack-like Wi-Fi router and its cellular connection, or similar.
Otherwise, no. HotSpot and 4G/3G connections will not permit iCloud backups.