Why is my system data 180 GB?
Why is system data taking up so much space? And why is there no easy way to unload it?
iPhone 11 Pro Max, iOS 16
That sounds like bogus Other Data.
You need to backup and restore the iphone
See here for the resources you need. Allow a couple of hours:
How to back up your iPhone, iPad, and iPod touch - Apple Support
Restore your iPhone, iPad, or iPod to factory settings - Apple Support
Restore your iPhone, iPad, or iPod touch from a backup - Apple Support
If it omes back in the coming weeks then you have a rogue app such as a badly designed game.