Where did my photos go?

This article may help in providing further information.

https://discussions.apple.com/docs/DOC-250002657

This paragraph really says it all

1. Syncing your devices. That is the primary purpose of iCloud Photos, to keep the Photos Library identical on all your devices. iCloud is keeping a copy of the current state of your Photos Library in iCloud as the master copy. When you modify your photos library on any device, it will be updated in iCloud and sync to all your devices. If you delete photos on your iPhone, the deletion will be updated in iCloud and on all other synced devices.

You are right that Photos maintains both the original file and the edited version. The benefit of iCloud Photos is that as soon as you make an edit on your Mac or take a photo on your phone; these photos are instantly sync'd and the edits copied across all of your devices. So you should always see the same edited version of your photo on all devices.

The same thing happens when you delete a photo on one of your devices, iCloud Photos will then delete the photo on all of your devices, just as it does with email and messages. This is good as it avoids you having to delete the photo multiple times. However, the photo is not completely deleted, it is moved to a 'recently deleted' folder or recycling bin for 30 days, after which it is permanently deleted.

For me, iCloud Photos fails the 'Backup service' test because all the devices are kept in sync at all times, there is no redundancy or separate copy of the photos, there is one live library and thats it. A few years back I lost the edits to 3,000 photos, there was no way I could retrieve these edits through iCloud Photos as no history is maintained, the only way I was able to recover these edits was through Time Machine which is a true backup service.

So, in summary, iCloud Photos is great, it does what it says it does, it means I can edit all my photos on the Mac and see the edited version on my phone and iPad without doing anything, but its important to also maintain backup copies in the event of problems.

Essentially there are 2 ways to maintain a library. When you import photos to the library you can either copy the photos into the library package (managed library) or just reference the photos in their existing location. The former is really the only option as many people have reported problems when using a referenced.

This article will explain it better than me.

https://discussions.apple.com/docs/DOC-250002591

In short one of the disadvantages of using a using a referenced library is that you could accidentally delete the photo without realising it is referenced in your photo library.

iCloud Photos is really just a syncing service to ensure all of your photos and edits are copied across all devices. If you are running out of space on your phone or Mac there is an option on both of them to 'optimise storage'. This option will manage the size of your library and where space is running short will replace the file with just a thumbnail of your photo.

Just to answer a couple of your specific questions.

The security of your photo files is only as good as the number of backups you make and where you keep them. At some point all hard drives will fail, so the key is to make multiple backups and keep at least one backup in a different location so that they are safe in the unlikely event of fire or theft. iCloud Photos is a good service, but should not be thought of as a back up service.

Yes, when you deleted the photos on your phone, this would have been instantly sync'd across all phones, iPad, Macs that you have which are signed into iCloud Photos.

You can maintain multiple libraries on your Mac. So you can have one library sync'd to iCloud Photos (and to all of your devices) and one library containing photos that you keep on your Mac only.

To do this, open Photos, press CMD , [COMMA KEY], this will open preferences. In the General tab you will see that 'Use as system library' is greyed out. You should make sure that 'Copy Photos to library' is ticked in the Import section, this will create a managed library. On the iCloud tab you will see iCloud Photos is ticked. You can either select Download originals or Optimise.

Close Photos.

Hold down the option key and click on the Photos icon, you will then be asked to which library to open and there is a button for create new library. Click create new library and you will now have a library that is completely separate from iCloud Photos and any photos you copy to this library will only be stored here and nowhere else.

You can choose whether to have a referenced or managed library depending on whether you tick 'Copy items to library' in the Preferences section - I don't recall what the default option is.

Your photos should have been in the 'Recently deleted' folder. Have you checked this?

Are you running a managed library? You should be.

Change where your files are stored in Photos on Mac - Apple Support