How to control iCloud Files not available in harddisc after only 1day ?

iCloud+ has 2 independent functions. iCloud backups, and iCloud sync. It’s confusing because they both have the same name prefix. But they have no connection with each other. Go to Settings/[your name]/iCloud. You will see a bunch of switches (with iOS 16 or later also tap Show All). When you turn on a switch that data type will sync to iCloud. If you do this on multiple devices that share an Apple ID the selected data will sync to all of those devices, and many data types will also be available by logging in to https://icloud.com. 

You can also turn on iCloud Backups. This will back up your phone every night if the phone is plugged in, connected to Wi-Fi and locked.

But note that these are independent functions; anything that you sync by the first method will be excluded from the iCloud backups.

You get other benefits with iCloud+

• Hide my Email, which lets you access websites without giving away your primary email account (and also track who they sell your identity to)
• Private Relay, which is sort of a super VPN (at much lower cost than commercial VPN)
• Custom email domain, so you can create a personalized email address that forwards to your Apple ID email (such as jane@doe.com)

dndrlsnn wrote:

and can you please describe the difference between a syncing service, and backup service that is syncing my files into a cloud :) ?

iCloud is syncing service. That means if you delete a file in one place, it deletes it on all of the devices. That would make a back up pretty useless. You wouldn't be able to recover something you deleted by mistake. A service that backs up files doesn't delete them from everywhere if you delete them in one place. Backups, once made, are not affected by what you subsequently do with your working files.

I suppose there may be cloud services that offer both syncing and backup. I don't know of any off the top of my head.

How do you know that they are not on your Mac, anymore? If I drag a file from my Documents folder to the iCloud Drive folder, that file will disappear from my Documents folder-- it's now "in" the iCloud folder. You could see it there on your iPhone or iPad, or at iCloud.com. It's also kept in an invisible folder in your Library. But the only way to access the file is to click on it in the iCloud Drive folder. Since a copy is stored in this invisible folder, when you click on it in iCloud Drive, the file should open quickly.

If storage space is at a premium on your Mac, the Mac will remove large files to make room for its use of the drive for management purposes. Apple recommends that at least 10% of your internal drive remain free, and I think that I've found that it would like even more than that-- when mine gets to more than 80% full, I start offloading files to an external drive--so the Mac won't. So, if the Mac perceives a storage problem, it may need to remove some files, and it may take longer to open these files, because they have to come from iCloud. It will remove a large file in preference to a bunch of little files, since, on average, you're more likely to need one of 50 files rather than 1 particular file.

Is it possible that this is what's going on?

You could save them locally to a external SSD or HD if you don't like waiting for iCloud.

iCloud is a syncing service, not a backup service (except for iPhones and iPads). It may not be the best choice for what you need.