garyfromStrfd wrote: … iCloud Photos are mirrored in Google photos. Not sure if this is part of problem because Google drive is almost full.
I don't know much about Google Photos, but the idea of including an extra thing in the synchronization makes my stomach hurt. Having no room in storage is a real headache, and with Google Drive you have one more source of headaches. I do sympathize with wanting to back up iCloud. The reason I back up iCloud (through my Mac to a hard drive) is that iCloud is automatic. So iCloud backs up mistakes well as pictures. A back should provide a copy before the mistakes. It sounds to me like mirroring to Google also automatically copies mistakes, so I wonder how useful that is.
On Apple devices, including iCloud, you need to keep at least 10% of the storage free. Are your lost pictures on Google Drive? If not, I think that they are gone.
You can see this:
If you're missing photos or videos in the Photos app - Apple Support
Basically the above says to look in Recently Deleted and in Hidden. Be sure to check your Library thoroughly-- the pictures may not be where you expect, as dates may have changed. You can use the search field with the date or location. And remember, you can sort the Library by date captured or by date added. Also, your Library view now has filters, and you may not have your filter set to "All Items:"

Let us know what you find…