OK, so I only have my new phone now (already wiped the old one – in retrospect rather hastily), but with the old one it of course did iCloud backups and I made sure to do one before I reset it.
I should mention, there was a LOT of shenanigans last night with EE and getting my eSIM working on the new phone, so I am extremely reluctant to reset everything. EE were great, it was just a faff and took a long time to sort.
So, if taking off and nuking from orbit is the only other option, maybe I am better just to do the apps one by one. Poop!
My old phone was on OS15.01, and the new one just on 15 initially, which it then updated. Maybe that caused the bug.
FWIW, I had an 8 plus, got a little frustrated with the size so went to a 2020 SE. loved the wee size, but hated battery life and really the screen was far too small for both my old eyes and fat fingers. Now on a 13 Pro – holy shit thats an lovely screen and phone to use. except for this bloody issue of course.