Apple Time Machine & iCloud

In addition to Niel's reply, be sure to familiarize yourself with what "iCloud Backup" actually does:

What does iCloud back up? - Apple Support

"iCloud Backup makes a copy of the information on your iPhone, iPad, and iPod touch."

Besides that fact, there are a lot of caveats regarding what actually gets backed up, and what is specifically excluded.

Time Machine excludes nothing, other than macOS itself, and whatever else you explicitly choose to exclude. It even backs up your iOS device backups, so that they can be completely restored without even having to rely on iCloud. This assumes you back up your iPhone / iPad to your Mac.

Read Backup methods for iPhone, iPad, and iPod touch - Apple Support.

Use that or a different Mac backup method. Apple's iCloud backup service is for iOS devices and iPads, not Macs.

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