In my case it is iPhone 13 pro ios 15.3 and I have systems data grown to 64 GB , loging out of I cloud , deleting history and websites settings in safari as deleting all icloud files did not help either My iphon‘s storage is reduced by half it is a scandal , re-booting doesn‘t help either, I had no iCloud-Photos bigger then 3-5GB deleted Icloud-photos did not help either and all tricks read on internet like mac-magazine and co are waste of time , do I get money back or Apple please sent me the bigger iPhone 13 pro with 256 GB so I can use 100 GB I payed for. thank you.