Nine months photos just vanished from iCloud and all devices

It is quite easy to have photos selected that are not visible on screen - for example if you have selected them (deliberately or accidentally) then scrolled to a different part of the library. If you then select on additional image and delete it you will also delete all other images that are already selected.

That is one way it is possible to accidentally delete images.

Some people also make the mistake of deleting items on their phone to create space, not realising that will also delete them from iCloud and all other devices.

I guess you have already checked your deleted items folder?

I know it won't help you, but for the benefit of anyone else reading:

iCloud IS NOT a backup...

The problem with iCloud for photos (and files if you use iCloud drive) is it makes all the libraries across all the devices the same. While it does protect you from a drive failure - it doesn't protect you from accidental deletion. If you delete photos on your phone, they are deleted on your mac, and from iCloud - same if you delete on your mac - they'll be deleted on your phone.

Every few days we get someone here saying "I deleted photos - how can I get them back". If it was more than 30 days ago (or they’ve been manually removed from recently deleted), and there is no other backup, the answer is "you can't"

Always use a proper backup in addition to iCloud.

Just something worth trying.

Follow the sequence of image file names from just before the missing ones. It should be possible to guess the filename of some of the missing images, by following the number sequence.

Try doing a search for a few of these both in photos, and in finder. This will tell you if they are actually still there, but have somehow got out of sequence in the library. Or if they are still somewhere on your mac.

The only way that Apple would ever delete photos from iCloud Photos would be, if you have been using more cloud storage than you have paid for for several months. Then Apple may delete older photos if you did not fix this after receiving a warning, that you are exceeding the cloud storage.

There are other possible ways that Photos may vanish from your devices:

• Does anyone else have access to your devices or your AppleID? In many cases it is a friend or family member who deleted the photos, when they got access to your device, just for the fun of it.
• There may have been photos or videos on your device, that never have been uploaded to iCloud at all, for example, because the format has been incompatible. If you then restore the device from iCloud, the items that have not been in iCloud cannot be restored.
• On an iPhone the most common reason for missing iCloud Photos are synced photos. Photos and videos you sync from a computer to the iPhone, are incompatible with iCloud Photos and will be instantly deleted from the iPhone, when you enable iCloud Photos.
• On a Mac the most common reason for missing photos is switching between Photos Libraries. This can easily happen, if you have external backup volumes connected and Photos is using a different library when you import photos then you usually are using. Try to check all external drives you have been using last year to see, if you can find your photos in a different Photos Library.
• And, do not look at the Recents album, when you are searching for photos from a certain year. Look at "All Photos" instead. The sorting in "recents" may change after a system upgrade, or whenever your Photos Library has been rebuild. All Photos is sorted by the date a photo has been taken, not the date you imported the photo. The capture date is unlike to change, while the date of Import may change, when a library has to be recreated.

BTW, which system version is installed on your Mac? Since macOS 14 Mojave we are not seeing all photos in the Library View, unless we are looking at the All Photos album. The months and years are showing only a selection of the photos. And the "Showing" Filter may be suppressing most of your photos.