Using Time Machine and iCloud

Time Machine is specific to MacOS and is a true archival backup system. That is, TM keeps old backups and makes new, separate incremental backups so you can go back in time to restore data. It also lets you restore individual files, folders or the entire device, from any given dated backup captured on your TM storage device.

With a Mac and icloud, you can use icloud to sync your files, but I would never consider that as a replacement for a TM backup.

iOS and iPadOS do not work with TM and do not offer any archival backup. Each iCloud backup (or iTunes) with an iOS or iPadOS device only ever saves a single instance, the most recent. Also iOS and iPadOS icloud or iTunes restore from backups are all or nothing restores - there is no selective feature or data restore with iOS nor iPadOS.

So no it is not redundant really, not in any sense of a truly redundant backup system. You could turn off icloud for just the Mac if you’re using TM. But you’d likely still want that for the iOS or iPadOS devices. The point of iCLoud for MacOS is to sync data across devices. But it is not at all a true archival backup system like TM is. For iOS and iPadOS, iCloud backups offer the convenience of once every 24hrs automatic backups.

I personally do not use iCloud with my Macs (2018 Mac Mini and 2015 MacBook Pro, since I do not need those to be in full sync with each other), but do use Time Machine, and CarbonCopyCloner with separate portable SSD drives for redundancy. My IPads and iPhones are backed up to iCloud (automatically every 24hrs) and to iTunes (on the Mac mini), again for redundancy.

In principle, redundant backup schemes are a very good thing. But iCloud sync for MacOS is not really an independent backup system - it is a synchronization service for Mac files. TM and some other method (e.g. CarbonCopyCloner device clones) would be redundant for MacOS. iCloud and iTunes backups for iOS and IPadOS would be redundant for IPads and iPhones.

When you cancel an iCloud subscription, it reverts back to the 5GB free storage allotment. After 30 days, anything you had in excess of 5GB is purged. So if using iCloud photo, yes, make sure to transfer everything to your computer first.

Nothing will be altered on your Mac or iPad unless the sync’d data gets purged without you disabling that sync setting in iCloud. So you want to disable Desktop and Documents first, then cancel the iCloud subscription.

So follow the directions in -> Transfer photos and videos from your iPhone, iPad, or iPod touch - Apple Support and Add your Desktop and Documents files to iCloud Drive - Apple Support

When not sync’ ing the whole Macs desktop and documents, you can still use iCloud Drive for individual apps - so still use it to sync Pages or Numbers files across devices.