ep, two years on and they still can't locate it

same problem. i eneded up upgrading to iPhone 15 pro with 256gb only to find that my system space gre from 3oish gigs to over 190. even spending GBP1000 on a new phone didn't fix the issue apple wants to help but has no idea why its happeneing

you will probably find it grows back to the original level after a week or so.

(192gb system space here!) there IS something with safari where tabs can be left open forever which grinds it to a halt eventually (I had that) but as you say it's not lined to storing tens and tens of gigs of unknown system storage