(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

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

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

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