MartinF103,
Since you're certain that the photos were not deleted from any of your devices, you may also want to verify that they are not hidden as well:
"Unhide your photos
If you hide photos and videos, you'll see them only in your Hidden album, so it might seem like they're missing. But you can unhide your photos and videos whenever you want. With iOS 14 and later, you can hide the Hidden album so it doesn't appear anywhere in the Photos app. So if you're missing photos or videos, make sure the Hidden album is turned on so you can see it.
If you use iCloud Photos, the photos that you hide on one device are hidden on your other devices too.
On your iPhone or iPad
- In the Photos app, go to the Albums tab.
- Tap Hidden under Utilities.
- In iOS 16, iPadOS 16.1, or later, use Face ID or Touch ID to unlock your Hidden album.
- Select the photo or video that you want to unhide.
- Tap the More button
, then tap Unhide.

On your Mac
- Open Photos and in the menu bar, click View, then select Show Hidden Photo Album.
- In the sidebar, select Hidden.
- In macOS Ventura or later, use Touch ID or your login password to unlock your Hidden album.
- Select the photo or video that you want to unhide.
- Control-click the photo, then choose Unhide Photo. You can also choose Image > Unhide Photo from the menu bar, or press Command-L."
More details here: If you're missing photos or videos in the Photos app
If the photos have not been hidden, we suggest that you reach out to Apple directly. They will be able to assist you further to determine why iCloud Photos is not working as expected. Click here to connect with them: Get Support
Best wishes!