I have iCloud Photos disabled and regularly delete photos (and clear them from recently deleted) so I was anxious to update and see if any old photos resurfaced.
After updating I did indeed have 1 previously deleted photo (an accidental lock screen screenshot, something I do regularly and always delete) from 2022 appear at the bottom of my "Recent Photos". I don't believe that I had iCloud Photos enabled at any point in 2022. I have had the same device for many years.
My best guess is that this remained on the device somewhere in an inaccessible state (deletion failed) and this software update has made it accessible again.
EDIT: I permanently deleted it again and restarted my phone and it didn't reappear