My Personal Library Photos have Disappeared and Only Show in the Shared Library

I recently reset my iPhone after sending it in for repair. Thankfully, I shared all my photos in a shared album with my partner beforehand. Since receiving the phone back and restoring via the iCloud backup, my personal photos ONLY show on the shared library. Each image also shows double. Only my screenshots now show up in my library. I contacted Apple Support and they were a bit stumped and recommended I delete the shared library and rejoin, but I'm really scared to do this as it's full of all the photos from our daughter's first six months of life. I'm scared that if I delete and rejoin, all my photos could be lost since there already seems to be a major glitch in the system. It's the same issue when I log into iCloud from my MacBook too. iCloud only shows my photos (and I'm talking about YEARS of photos) when I'm in the shared library. If I go to my personal library, only photos I've taken since my phone was returned appear there.