Ventura System Data - A Mystery.

Part 1 of 2

There is Purgeable Space and there is Empty Space.

Purgeable Space which is Controlled by the Operating System. When the Operating Systems decides the computer needs additional Empty Space, it will move a portion of the Purgeable to Empty space

AFAIK - there is no User Actions to hasten this transition from Purgeable to Empty Space

It can day or longer before this will occur  

The links below will assist in identifying what is taking up space on the Internal Drive and provide possible ways to remove data that is under the direct control of the User ( Home Folder ) . 

Rebuild the Spotlight index on your Mac

What is “Other” storage on a Mac, and how can I clean it out?

Free up storage space on your Mac

OmniDiskSweeper Safe to use

GrandPerspective 

How to delete Time Machine snapshots on your Mac.  

Often caused if the Time Machine Drive has not been attached  to the computer and TM Backup is set to run on a Schedule. 

TM Backup will make Snap Shot on the Internal Drive awaiting the TM Backup Drive to be attached. 

Only then will the Snaps Shots be transferred to the External Drive and deleted the Internal Drive.

See used and available storage space on your Mac

Locate backups of your iPhone, iPad, and iPod touch

Notation - If the user is using a cloning software like Carbon Copy Cloner - suggest tweaking the Safety Net Feature in this software. It may be making additional Snap Shots that are not being Cloned to the Eternal Drive. If this should be the case, these Snap Shot could be using additional space on the drive 

The final word from Apple on Managing the " Other/ System Data “ Category

Other / System Data: Contains files that don’t fall into the categories listed here. This category primarily includes files and data used by the system, such as log files, caches, VM files, and other runtime system resources. Also included are temporary files, fonts, app support files, and plug-ins. You can't manage the contents of this category. The contents are managed by macOS, and the category varies in size depending on the current state of your Mac.

Part 2 of 2

The user ( you ) can remove Some Applications.

Just None of the Applications that are built Into the Operating System.

Example : News, Music, Freeform, Maps, TV etc

Starting in macOS 11 Big Sur and above. 

The Operating System resides in a Sealed and Read Only Volume that can not be opened by the User nor by Third Party Applications.

The only Entity that can open and modify or alter this Volume is Apple.

Should this be not to uses liking >>

 Product Feedback - Apple and make it known to Apple regarding this.

TimebasedanalysisBob wrote:

Why can't I remove all those apps I don't need. OK, they are only taking up about 1.2GB on the SSD but it's the principle of fine tuning by the owner.

The apps preinstalled are located in the read only system volume and can't be removed.

By way of The Voice of the Customer. A communication to Apple. Please can you modify the OS so customers can have a little bit more control over system adjustments.

You can send Apple feedback.

Feedback - macOS - Apple

TimebasedanalysisBob wrote:

My data file is currently at 19GB, when I installed Ventura 13.4.1 it grew from 13GB to 19Gb instantly. OK, I understand that the MAC OS keeps the old files a bit whilst the new ones are being installed and stabilised.

I don't know what you mean by "data file". If you are unfamiliar with the Mac, it might be helpful to post a screen shot of what you are asking about.

Generally speaking, 4 GB (or 40 GB) of data usage here and there is normal. I recommend not looking too deeply. I've seen people literally lose their minds doing that.

But why does it take so long to remove the old installation files and other historical files?

Again, I don't know what you mean here. It actually isn't possible to remove old installation files or historical items and you shouldn't attempt to do so. The operating system manages all of these things. You shouldn't go investigating on your own. No good will come of it.

Why can't I remove all those apps I don't need. OK, they are only taking up about 1.2GB on the SSD but it's the principle of fine tuning by the owner.

You're in the Apple world now. You have relinquished your ownership and control. You will have to judge for yourself whether or not that was a net gain.

By way of The Voice of the Customer. A communication to Apple. Please can you modify the OS so customers can have a little bit more control over system adjustments.

This is a user-to-user tech support forum. Apple isn't here. You cannot modify the operating system except as provided by the user interface. Even then, I strongly recommend sticking with defaults.

The bottom line - The MacBook Air M2 13 inch is a great machine.

So why mess with a great thing? Serious question.

Welcome