So I have been using a company given iPhone 14 as my main device until January 2024 where I got myself an additional 15pro max- I want to keep job and private things separate and also a pro model iPhone.
During the setup of the 15pm I transferred my data from the 14 to the 15 via the QuickStart function-not using the iCloud though but the direct transfer as described here
https://support.apple.com/en-us/HT210216
I do not use iCloud Photos or iCloud backup because I don’t trust cloud services. All my devices share the same Apple ID.
After everything was transferred I did not wipe the iPhone 14 but deleted everything not needed for my job including my personal photos stored locally on that phone manually.
Last week I updated my IPhone 14 first, then one day later my 15pm. When I read about old deleted photos coming back I thought that this is limited to users who use the iCloud. Still I checked my 15pm and in my recent photos I found a file which was not an image but showed “large thumbnail” as text. The information of that file which can be shown inside the gallery was not helpful and I just deleted this file. Then some time later after this and other threads blowing up I got bugged more and more and then remembered to check my 14 too. Remember I deleted every photo after transferring everything to the 15pm in January.
And there again I could see the “large thumbnail” file and additionally there was a screenshot of my home screen I probably took accidentally last year and deleted immediately. Then I went through the gallery of my 15pm and found exactly that screenshot with the identical time stamp. So on both phones the same screenshot came back and I believe the file was not deleted properly last year on my 14 and then transferred in that state to my 15pm. The latest update made that screenshot reappear on both phones.
Additionally I have an iPad Pro which I had not updated yet. Therefore I deleted every photo I had on it, made sure that the files are also deleted from the “to be deleted in 30 days” section, restarted the device once and then ran the update on it.
One screenshot I again must have taken accidentally on the iPad returned.