Photostream - Help!

The "All Photos" view is showing the photos in your library plus my Photo Stream. So Photos may vanish from "All Photos" after you delete from My Photo Stream.

To check, if the photos are still in your library, look for them in the "Photos" view with the Moments, Collections, Years. Photos, that have been safely imported to the library will appear in the Photos view. Before deleting a photo from my Photo Stream, check, if it already has been imported to the Moments.

Frankly, I would not delete photos from my Photo Stream, unless they are poor photos, that I do not want to keep anyway. All photos will vanish from My Photo Stream after 30 days automatically, and we do not risk to delete them from the library, if we wait for the automatic deletion.

I need to clarify this before I delete the 996 photos on my iPhone to free up space. I want to make sure these photos which are presently all in "All Photos" on the Mac will not delete also.

If your goal is to free storage on the iPhone, delete the photos from the Moments on the iPhone, and not from My Photo Steam. Then you can be sure, that the photos will not be deleted from the Mac.

The documentation for My Photos Stream is contradictory. And the behavior has changed between system versions. That is probably the reason, why you are getting no conclusive answers from Apple Support. Your first observation:

Image shot on iPhone. Image appears in Mac Photostream and Mac "All Photos".

Image deleted on iPhone and gone from Mac Photostream but not gone from Mac "All Photos"

This consistent with the documentation in the iPhone User Guide:

https://help.apple.com/iphone/12/#/iphbfeb468fc

It says:

Delete photos: Select the photos, then tap .

Although deleted photos are removed from My Photo Stream on all your devices, the original photos remain in Photos on the device on which they were taken. Photos that you save to another album on a device or computer also aren’t deleted."

So, if you delete photos on the iPhone from My Photo Stream hat have been taken on the iPhone, they will remain on the iPhone and not be deleted from the device, only from my Photo Stream.

Image shot on iPhone. Image appears in Mac Photostream and Mac "All Photos".

Image deleted in Mac Photostream, gone from Mac All Photos and iPhone.

But have you checked, if the photo in question is still in the Moments on the Mac? "All Photos" is a weird mixture of My Photo Stream and all photos in the library and it is strangely sorted by the date of import.

It is hard to tell, if a photo is in All Photos.

Your Mac is supposed to import all photos from my Photo Stream to the library, automatically. Photos saved to the library should stay in the library (Moments, Collections, Years), even if you no longer are seeing them in My Photo Stream.

Can you confirm, that the photos you are no loner seeing in all Photos are gone from Moments, Collections, Years as well? That would be a bug.

Then the automatic import from My Photo Stream to the Photos Library on your Mac is not working reliably. Have you ever repaired your Photos Library? (https://support.apple.com/guide/photos/repair-the-library-pht6be18f93/mac)

Have you tested, if the photos will stay in "All Photos", if you manually import from My Photo Stream by dragging the photos to the sidebar to create an album? I cannot test any of this any longer, because I have iCloud Photo Library enabled and my Photo Stream does not show at all in Photos on my Macs.

It will be much safer by far, if you only delete from the Moments on your iPhone and not from my Photo Stream. It is just too buggy and risky.

Also there are currently 996 photos in my Photostream folder on my iPhone where as there are only 45 images in photo stream on my Mac?

That is expected and has always been this way. The number of photos in my Photo Stream usually differ on all devices. They will depend on when you last reset My Photo Stream on each device. My Photo Stream can hold up to 1000 photos on each device and in iCloud. The devices download the photos from My Photo Stream and keep a local copy of the stream. In iCloud older photos will be removed after thirty days. But each device may be keeping the photos longer in their local copy, if the space permits it. When you turn off my Photo Stream on a device, the local copies will be removed. When you then turn on My Photo Stream again, the device will download what is currently still stored in iCloud. That will usually be less photos than. After turning off My Photo Stream on all devices and turning it on again, the numbers should be equal on all devices (after the devices had time to sync). But naturally you need to save all photos you want to keep in the Photos Library, before you disable My Photo Stream.

See the paragraph "I see different photos in the My Photo Stream album on each of my devices" in this document:

Get help with My Photo Stream - Apple Support

See these articles My Photo Stream - Apple Support

iCloud: What is My Photo Stream?