And this is what I've submitted via Feedback - Camera - Apple:
Prior to iOS 18, the Photos app provided a folder called "Recents" where a user could review the photos they'd taken using that phone (as well as photos saved from messages, screenshots, etc) in order to decide which to keep, which to upload to their Mac, etc. In iOS 18, the Photos app lost that functionality. The photos described above are shown mixed up with photos synced from other sources.
At https://discussions.apple.com/thread/255760698, I see that there's a clumsy workaround in the Camera app but on my iPhone the Camera app displays the text “No Photos or Videos".
I had turned on the "Use Face ID” setting in Settings > Photos as an experiment. Though I've turned it off, the Photos app still says “Face ID Required to open Photos”. Could this be causing the Camera app problem?