System data is filling up storage on iPhone 11 despite minimal app and media usage

I have an old IPhone 11 that is working perfectly fine except that the phone has no storage as it taken up by ‘system data’. I have stripped the phone back to a set of minimum apps that I cannot live without. Even those are automatically offloaded by the phone on a weekly basis. I have no music on the phone and 8 Gb of photos which which the phone also controls. Whatsapp is the next biggest app with 2GB where I regularly remove any large video files. I cannot install system updates as their is no free space.

i have tried all the tricks such as restarts, sign out of iCloud and back in, change to a future date and back. These reduce the system data a bit, but it the quickly grows again. This started about 6 months ago and was never a problem before that. My daughters iPhone 15 is packed with apps, games, music, movies etc and the system data is 3Gb. The nuclear option is to reset the phone and restore from backup, but would like to avoid that if possible.

When are Apple going to fix this? There are so may posts highlighting the same issue. It feels like I have triggered the ‘time to buy a new phone’ subroutines. If this can’t be fixed, I will buy a new phone, but it won’t be an Apple product.

[Re-Titled by Moderator]

Original Title: Phone 11 64GB with 23GB of ‘system data’